To provide a dimension measuring device for eliminating the redoing of reference matching and improving the work efficiency.

This dimension measuring device is provided with a gauge main body 10 provided with a rotatable measure plate 4 on a front surface, a spindle 11 passed through the gauge main body 10 and energized upwards, gears 12, 13 and 14 pivotally supported so as to be engaged with the rack part of the spindle 11 and transmit rotation to a pointer 5 rotated on the measure plate 4, supporting bases 6 and 7 for covering the spindle 11 projected downwards from the gauge main body 10 and supporting the gauge main body 10 and a measuring piece 3 fixed to the spindle 11 so as to be projected in the horizontal direction from the slit 7a of the supporting base 7 formed in the vertical direction.