Once-a-day Immunosuppression(CISECON_a_day)

Inclusion Criteria: * Men or women at the age of 20 to 65 who had kidney transplantations at least 3 months ago. * Recipients of kidney transplantations from a deceased / cadaveric donor, non-heart beating cadaveric donor / organ donor after cardiac death, or non-blood related or blood related live donor. * Patients being treated with Tacrolimus or Extended Release Tacrolimus as the existing immunosuppressant maintenance therapy. * Able and willing to give informed consent to study participation, having signed the informed consent form according to appropriate procedures, and capable of participating in the study by making visits according to study plans. Exclusion Criteria: * HIV, HBsAg, or anti-HCV test positive patients or having received kidney transplantations from an HIV, HBsAg, or anti-HCV test positive donor. * History of severe allergies or hypersensitivities to drugs used in the study or other drugs with a similar chemical structure requiring acute (within the past 4 weeks) or chronic treatment. * Having received other investigational product within 30 days prior to enrollment into this study. * Women of childbearing potential who plan to become pregnant, pregnant and/or lactating women, women who do not intend to use effective contraceptives. * Having uncontrolled diseases or medical conditions requiring continuous treatment. * History of alcohol or drug addiction within the past 3 months or incapable of appropriate communications due to reasons such as mental illness. * Absolute neutrophil count \<1,500/mm3 or leukocyte count \<2,500/mm3 or platelet count \<75,000/mm3 at screening or severe metabolic disorders (including functional disorders). * Having experienced the following condition within the past 1 month: * Serum creatinine \> 2.0 mg/dl more than twice. * 24 hr urine protein≥750 mg/day * Diagnosed with or treated for a rejection reaction or an infection or hospitalized due to other medical reasons.