A semiconductor controlled rectifier device comprises a semiconductor substrate consisting of a plurality of layers of alternately different conductivity types, in which the outermost layer exposed at one of the principal surfaces is divided into a first portion providing a main thyristor, and a second portion having an area smaller than that of the first portion and providing an auxiliary thyristor. In the device, the second portion of the outermost layer of the substrate comprises a first region participating in the turn-on of the device, and a second region acting to increase the minimum gate current necessary to turn on the device, thereby increasing the minimum gate current necessary to turn on the auxiliary thyristor without appreciably increasing the gate current required for turning on the auxiliary thyristor and without reducing the switching power capability of the device, so that mal-firing due to noise current induced between the gate and the cathode can be prevented.