To provide a device for measuring, with precision, the distance between the centers of a crank shaft journal and a pin, while eliminating affect from changes in diameter dimension of the journal and the pin.

On a plate 12 connecting a pair of V-type supporting parts 7a and 7b placed on journals 1a and 1b of a crank shaft, a dial gauge 5 is attached through the second plate 14. Into a supporting block 11 integrated with the plate 12, a rocking amount of a V-type arm 8 contacting to a pin 1c to which the V-type arm 8 is freely rockably attached through an axis 10 presses in the measurement part of the dial gauge 5 through a measurement arm 13. With this configuration, the distance between centers is accurately measured irrespective of changes in diameter dimension of the journals 1a and 1b and the pin 1c.