The purpose of this study is to evaluate the efficacy and Safety after conversion to TacroBell SR cap. or TacroBell cap. in patients who in renal transplant patients undergoing maintenance therapy with Reference Tacrolimus.

This study is a multi-center, Randomized, Open-label and phase IV clinical trial that evaluates the efficacy and safety after conversion to TacroBell SR cap. or TacroBell cap. administration for 24 weeks in renal transplant patients undergoing maintenance therapy with Reference Tacrolimus.

Inclusion Criteria:

• Over 20 years old(male or female)
• Patients with eGFR (By CKD-EPI) ≥30mL/min/1.73m^2 and spot urine P/C ratio≤0.5 at screening test
• Patients who are taking Tacrolimus twice a day for maintenance therapy and have Trough level of 3~10ng/ml
• Agreement with written informed consent

Exclusion Criteria:

• Patients who have transplanted organs other than kidney
• Patients with acute rejection who have been clinically treated within the last month
• Patients who have changed their administration of adjuvant immunosuppressants and corticosteroids within the last month (dose change, discontinuation, etc.)
• Patients who have been diagnosed with cancer within the last 5 years (except skin cancer or thyroid cancer determined by the investigator that treatment has been completed)
• Patients deemed inappropriate for screening due to severe digestive disorders at screening
• Patients with severe systemic infections requiring treatment (transplantation may be possible after the infection is completely lost or controlled)
• Patients with genetic problems of galactose-intolerance, Lapp lactose deficiency or glucose-galactose malabsorption
• If the following cases occur during screening
• Treatment of active liver disease or increased one or more of the liver function tests (T-bilirubin, AST, ALT) levels more than three times the upper limit of normal range
• Patients with WBC <2,500/mm^3, PLT <75,000/mm^3, ANC <1,300/μL
• Patients who have experienced hypersensitivity reactions or serious abnormalities with medicines used in this clinical trial or with similar chemical structures (Tacrolimus, etc.)
• Pregnant or lactating women
• Patients of childbearing potential who do not agree to the proper use of contraception during the trial
• Patients who received other investigational drugs within 4 weeks prior to consent of the document
• Patients unable to participate in the clinical trial due to the judgment of other investigators