A cartridge transferring robot for use in a library apparatus which is capable of improving the accuracy of the cartridge inserting/extracting angle of a hand mechanism and further of ensuring the positional accuracy of the tip portion of the hand mechanism sufficient for direct insertion and extraction of a cartridge into/from a drive unit. In the present invention, for these purposes, a tilt mechanism for adjusting the angle of the cartridge inserting/extracting direction with respect to a horizontal plane is composed of a tilt base for supporting a picker section so that the picker section is swingable around a supporting shaft located on a picker section front surface side facing a place for insertion or extraction of the cartridge, and a swinging drive mechanism disposed on the rear side of the picker section for making the picker section swing around the supporting shaft with respect to the tilt base. Further, this invention is for transferring cartridges among a storage unit, a cartridge entry/exit station and a drive unit within a library apparatus storing a large number of cartridges such as magnetic tape cartridges and optical disk cartridges.