A therapeutic and/or prophylactic agent for restenosis, which comprises a thiadiazoline derivative represented by the general formula (0), or a pharmaceutically acceptable salt thereof: [wherein, n represents an integer of 1 to 3, R0 represents aryl, —NR1CONR2 (wherein R1 represents a hydrogen atom or the like, and R2 represents lower alkyl or the like) or the like, R3 represents lower alkyl, R4 represents a hydrogen atom or the like, and R5 represents aryl or the like].