Therapeutic Confirmatory Study to Evaluate the Efficacy and Safety of Avanafil

Inclusion Criteria: * male subjects aged 19 to 70 with history of erectile dysfunction for at least 6 months * subjects have stable monogamous relationships * their partners are free from pregnancy and lactation and well prevent conception * subjects consented to participate in the clinical study in writing * subjects attempted sexual intercourse at least 4 times in separate days during 4 weeks' free run-in period, and failure rate is over 50% Exclusion Criteria: * history of spinal cord injury or radical prostatectomy * subjects whose penises are anatomically deformed * erectile dysfunction due to neurogenic or endocrine cause * subjects who have uncontrolled major psychiatric disorder and do not accept therapies or have significant neurological abnormalities * history of cancer chemotherapy within 1 year * subjects who are addicted to alcohol or have continuously misused dependent drugs * subjects who have hepatic dysfunction(GOP,GPT ≥ 3xUNL) or renal dysfunctions(serum creatinine \> 2.0) * subjects who have uncontrollable diabetes(FPG\>180) * subjects sho have proliferative diabetic retinopathy * history of stroke, transient ischemic attacks, myocardial infarction, heart failure that needs to be medically treated, unstable angina or fatal arrhythmia or coronary artery bypass graft within 6 months * serious hypotension or uncontrollable severe hypertension * hematological disorders that is likely to be developed into priapism such as sickle cell disease, multiple myeloma, leukemia * subjects who have retinitis pigmentosa * subjects who suffered from serious GI bleeding disorder within 1 year * subjects who took other PDE5 inhibitors or ED therapies within 2 weeks * subjects who use non-concomitant medications(Nitrate/NO donors, Androgens, anti-androgen, trazodone, Anticoagulant,over-the-counter drugs known to inhibit the activity of CYP3A4) * history of hypersensitivity to the PDE5 inhibitors or not responded to them * subjects who have hypoactive sexual desire * subjects who have no intention of having sexual intercourses 4 times in separate days during 4 weeks' free run-in period * subjects who took other investigational products within 30 days before this clinical study * subjects who are judged to be unsuitable to the clinical study by other reasons