Bioequivalence Evaluation of a New and Current Tablet of ASP015K

Inclusion Criteria: * 50.0 kg ≤ body weight at screening \< 80.0 kg * 17.6 ≤ BMI at screening \< 26.4 \[BMI = Body weight (kg) / (Body height (m))2\] * Subjects who agree to use the following highly effective contraception consisting of two forms of birth control (at least one of which must be a barrier method) starting at written informed consent through 90 days after the study drug administration in Period 2. * Subjects who agree not to donate sperm starting at informed consent through 90 days after the study drug administration in Period 2. * Subjects judged as healthy by investigator or sub-investigator based on physical examinations (subjective symptoms and objective findings) and all clinical tests obtained at screening and from check-in to immediately before the study drug administration in Period 1. Exclusion Criteria: * Subjects who have received investigational drugs within 120 days prior to screening or who plan to receive investigational drugs from screening assessment to check-in in Period 1 (Day -1). * Any blood donation or blood drawing apply the following: * Whole blood collection (≥ 400 mL): from 90 days prior to screening to check-in in Period 1 (Day -1) * Whole blood collection (≥ 200 mL): from 30 days prior to screening to check-in in Period 1 (Day -1) * Platelet or plasma donation: from 30 days prior to screening to check-in in Period 1 (Day -1) * Subjects who had used or plan to use any prescribed or non-prescribed drugs within 7 days prior to check-in in Period 1 (Day -1). * Any deviation of blood pressure, pulse, body temperature, or 12-lead ECG at screening or check-in in Period 1 (Day -1) from the following normal range: * Supine pressure: Systolic: ≥ 90 mmHg, ≤ 140 mmHg; Diastolic: ≥ 40 mmHg, ≤ 90 mmHg * Supine pulse: ≥ 40 bpm, ≤ 99 bpm * Axillary temperature: ≥ 35.0 ºC, ≤ 37.0 ºC * 12-lead ECG: Normal or clinically irrelevant abnormality QTc interval: ≥ 330 msec, \< 430 msec * Any deviation of laboratory tests at Screening or on Day -1 (check-in) in Period 1 from the following normal range. Normal range of each test at the test or assay site will be used. * Hematology: \> 20% of upper limit or \< 20% of lower limit. * Chemistry: deviation of ALT, AST, Cre, blood electrolytes (Na, K, Cl), or fasting blood glucose. \> 20% of upper limit or \< 20% of lower limit in other than above tests; however no lower limit is set with respect to ALT, AST, γ-GTP, T-Bil, ALP, LDH, CK, T-Cho, TG, Cre, and UA. * Urinalysis (qualitative): deviation in any of the urinalysis. * Urinary drug abuse test: positive for benzodiazepines, cocaine-based narcotics, analeptic drugs, cannabis, barbituric acid derivatives, morphine-based narcotics, phencyclidines, or tricyclic antidepressants. * Immunological test: positive for HBs antigen, HBc antibody, HCV antibody, HIV antigen or antibody, or syphilis. * Subjects who have any history or complication of drug allergies. * Subjects who have a history of upper gastrointestinal symptoms, i.e. nausea, vomit, stomach ache, etc. within 7 days prior to check-in in Period 1 (Day -1). * Subjects who have any history or complication of hepatic disease, i.e. viral hepatitis, drug induced liver injury, hepatic dysfunction, etc. * Subjects who have any history or complication of cardiac disease, i.e. congestive heart failure, angina, arrhythmia requires a treatment, etc. * Subjects who have any history or complication of respiratory disease, i.e. bronchial asthma, chronic bronchitis, pneumonitis, etc. (except for a history of asthma in childhood) * Subjects who have any history or complication of gastrointestinal disease, i.e. peptic ulcer, reflux esophagitis, etc. (except for a history of appendicitis) * Subjects who have any history of gastrointestinal resection (except for a history of appendectomy) * Subjects who have any history or complication of renal disease, i.e. acute renal failure, glomerulonephritis, intestinal nephritis, etc. * Subjects who have any history or complication of endocrine disease, i.e. hyperthyroidism, abnormality of growth hormone, etc. * Subjects who have any history or complication of cerebrovascular disorder, i.e. cerebral infarction. * Subjects who have any history or complication of malignant tumor. * Subjects who have any history or complication of congenital short QT syndrome. * Subjects who have any history or complication of lymphatic disease, i.e. lymphoproliferative disease. * Subjects any of the following apply regarding tuberculosis: * History of active tuberculosis * Abnormality in chest X-ray test at screening * Contact with patients with infectious tuberculosis * Subjects any of the following apply regarding infectious disease other than tuberculosis: * History or complication of serious herpes zoster or disseminated herpes zoster * More than once relapse of localized herpes zoster * Hospitalization due to serious infection within 90 days before check-in in Period 1 (Day -1) * I.V. antibiotics treatment within 90 days before check-in in Period 1 (Day -1) (except for prevention use) * Judged as prone to infections by investigator or sub-investigator, i.e. subjects with urethral catheterization. * Subjects who have any history of inoculation of live vaccine or attenuated live vaccine within 56 days prior to check-in in Period 1 (Day -1). * Subjects who have any history of clinically serious allergy (Clinically serious allergy; allergy induced systemic urticaria or anaphylactic shock require hospitalization when exposed to specific antigens or drugs). * Subjects who have any history or complication of heart failure classified as NYHA Class III or IV. * Subjects who have a history of ASP015K administration. * Subjects with excessive alcohol drinking or smoking. * Criteria for "excessive": 1. Smoking: ≥ 20 cigarettes/day 2. Alcohol drinking: ≥ 45 g/day (a large bottle of beer contains 25 g of alcohol, 1 gou of Japanese sake contains 22 g of alcohol) * Employee of the sponsor, CROs or study site involved in this study. * Subjects judged as inappropriate for the study by investigator or sub-investigators.