To provide a machine tool which enables in-machine measurement of workpiece dimensions, and achieves both size reduction and extension of a sensor life.

The machine tool for machining a workpiece 12 held by a spindle 2 comprises: a turret tool post 7 having a plurality of tool mounting faces; a support strut 22 mounted on one of the tool mounting faces and extending in a radial direction of the turret tool post 7; the sensor 24 fixed to a head portion 22b of the support strut 22 and measuring the dimensions of the workpiece; and a cover piece 25 and a cover piece 26 supported to a base portion 21 of the support strut 22. The cover piece 25 and the cover piece 26 are opened and closed in the circumferential direction of the turret tool post 7, and cover the support strut 22 and the sensor 24 in the closed position.