A threaded shaft measuring device includes a table that supports a threaded shaft to be measured, and that is capable of adjusting a rotation position about a perpendicular Z axis, adjusting a rotation position about an X axis that is horizontal and intersects with the Z axis, and adjusting a position in a Y axis direction that is horizontal and intersects with the X axis; and a stylus that performs scanning measurement of a surface of the threaded shaft. An adjustment jig capable of making contact with the threaded shaft and an elevator that brings the adjustment jig into contact with the threaded shaft are installed on the table. The adjustment jig includes an abutting bottom surface; an abutting side surface; a measurement surface; and an axis line marker that enables a tilt relative to the X axis to be detected.