To provide a compound that has excellent oral absorbency and can inhibit Prostate Cancer Antigen-1(PCA-1) enzyme activity.SOLUTION : The present invention provides a compound represented by formula (I) or a pharmaceutically acceptable salt thereof. (Ris H, -SONR' R' ' or a substituent; R' and R' ' independently represent H or a substituent, or may together form a ring; Ris a substituent; Ris H or a substituent; Rand Rmay together form a ring; where, if Rand Rdo not form a ring, Ris -SONR' R' ' ).SELECTED DRAWING : None