A belt attachment jig includes a jig body (10) located along a side surface of a pulley (1), and a belt guide portion (15) which protrudes forward in the pulley rotational direction from a contact portion (11) near one end of the jig body (10). The belt (B) is held between the twisting preventing plate (12) which forms the other end of the jig body (10) and the side surface of the jig-attached pulley (1) such that an inner circumferential surface of the belt (B) faces the jig-attached pulley (1). As the pulley (1) is rotated, the belt attachment jig is moved in the pulley rotational direction together with the belt (B) in a manner that makes the belt (B) fitted in the pulley groove.