An alignment mechanism includes: an adjusting plate having first and second adjustment ends parallel to an X axis direction; a probe fixing portion provided to the adjusting plate; a probe fixed to the probe fixing portion; a reinforcing plate having first and second base ends parallel to the X axis direction, displacement of the reinforcing portion in a Y axis direction being restricted; Y-direction adjusting screws for pressing the adjusting plate in the Y axis direction; and adjustment connectors for respectively connecting the first adjustment end with the first base end and the second adjustment end with the second base end. A stylus of the probe is disposed on a line of intersection of a first inclined surface including the first adjustment end and the first base end and a second inclined surface including the second adjustment end and the second base end.