A cassette library apparatus includes a swing arm (16a) provided at a swing frame (34) provided at a picker (15) to be swingable up and down, and swingable integrally with the swing frame (34), an engaging part (18) provided at a tip end of the swing arm (16a) and linked to an upward swing motion of the swing arm (16a) to be able to get into a recessed part (10a) of the cassette (1) from below, and a nut-shaped body (48) which is mounted to the swing frame (34) and screwed onto a feed screw (47) provided at the picker in an up-and-down direction, and swings the swing frame (34) by the operation of the feed screw (47).