PURPOSE: To speed up positioning of a workpiece by making the V groove of the tip end of the probe of a positioning indicator abut against a reference pin through lowering a spindle, moving a table so as to make the indication value of a gauze zero (0), and thereby adjusting the reference scale to be zero.

CONSTITUTION: When a workpiece 40 is set on a table 51 with a reference pin 45 being fitted in the reference hole of the workpiece 40 and a sleeve 5 of a positioning indicator 1 is fitted to a spindle 50, a probe 20 moves to an upper end, then a dial gauge indicator 30 shows minus (-) graduation. Further, when a pin 45 is moved right under the probe 20 and the indicator 1 is lowered, and when a groove 23 is made to abut against the pin 45 and the indicator 1 is further lowered, force for pushing the groove 23 in the radial direction of the sleeve 5 is generated and the probe 20 is moved in the radial direction until the slant face of the groove 23 abuts against the peripheral face of the pin 45. Furthermore, when an probe 32 is pushed and pressed according to the movement of the probe 20 and the dial gauge 30 is moved so as to move the pin 45 to make the indication value zero, the spindle 50 and the pin 45 are thus aligned with each other, and then if the reference scale 52 of the table 51 is set to be zero, positioning of the workpiece is speedily completed.