The present invention provides an electric locking device which has a simple structure, with which an operating time can be saved, and which has a sufficient clamping force required for operation. To a camshaft coupled to an electric motor through a speed reducing mechanism, a first cam and a second cam conjugate with each other are coupled. The first cam drives an arm driving rod in a clamping direction and the second cam drives the arm driving rod in a returning direction. Rotational motions of the first and second cams are converted into linear motions in the same direction by first and second cam contacting members supported by the arm driving rod. The arm driving rod drives a clamping arm to cause the arm to carry out a clamping operation. A cam face is provided as to move the clamping arm at a high speed until the arm reaches a vicinity of an end and to move the arm at a lower speed after the arm has reached the vicinity of the end.