To efficiently drive a rotation indexing unit by decreasing a power loss accompanied by a sliding resistance, by further decreasing a size of a rotary joint included in the rotation indexing unit, and decreasing an area of a sliding face in the rotary joint.

The rotation indexing unit (1) for a machining tool includes: a rotation shaft (6) rotatably provided in a frame (2), for supporting a rotary driven object (10); and rotary joints (15, 32) for supplying machining fluid to the rotary driven object (10), wherein a plurality of cables (27, 43) pulled out from the rotary driven object (10) are arranged in a state of inserting through the frame (2) in an axial direction of the rotation shaft (6). In this rotation indexing unit (1), at least one of the cables (27) is arranged outside of an outer peripheral surface of a hollow cylindrical part (17) of a member positioned radially outside of a distributor (16) and a shaft (21) constituting a sliding part of the rotary joint (15).