Provided is a tool rest for a machine tool, capable of smoothly engaging and releasing a tool-side engagement piece and a support-side engagement piece which releasably engage in accordance with movement of the tool. A first drive power transmission part (51) is provided between a mounted-part rotation transmission shaft (90) on the tool rest body (11) side and a first rotation drive power transmission shaft (81) on the tool mounting part (15) side, for transmitting rotary drive power from the mounted-part rotation transmission shaft (90) side to the first rotation drive power transmission shaft (81) side. The first drive power transmission part (51) comprises: a groove section (97a) formed on the tip of a slide shaft (97) of the mounted-part rotation transmission shaft (90); a tenon-shaped projection section (92) formed on the first rotation drive power transmission shaft (81) for releasably engaging with the groove section (97a); and projections (93a, 93b) for pressing against the groove section (97a), which is biased towards an engagement orientation when in the disengaged state, and temporarily releasing the engagement orientation, during movement of the tool to a designated position.