To provide a wheel measuring device which can measure the dimensions of respective parts such as the diameter of even a train wheel not having a reference groove at an inner side surface during running with no contact.

The position of a flange front end is measured with light sources 20, 21 for irradiating linear light to the front and rear of a wheel 1 and cameras 23, 24 mounted as one set respectively and the front end of the central flange front end of the wheel 1 is measured with the light source 22 for irradiating the linear light from the side face of the wheel and the camera 25. An image signal processing device 26 calculates the flange front end positions at three positions of the wheel from the images shot by the three cameras 23, 24, 25 to calculate the diameter of the flange from the three flange front end positions.