To provide a distance detector the manufacturing cost of which is reduced by reducing the number of parts.

A time measuring means, which starts time measurement upon receiving a control pulse from a light emission control means, is provided with a first switch means 26 which lets the control pulse from the light emission control means pass and stops the passing of the pulse by means of the leading edge of the output of a comparing means 22; first integration circuits 28 and 29 which integrate the light emission control pulse passed through the first switch means 26; a second switch 27 which is connected in parallel with the first switch means 26, lets the control pulse from the light emission control means pass, and stops the passing of the pulse by means of the trailing edge of the output of the comparing means 22; and second CR integration circuits which integrate the light emission control pulse passed through the second switch means 27, and supply the integrated outputs of the first and second integrating means to a distance calculating means which calculates the distance to a front target.