Disclosed is a security switch, which has a switch head (comprising actuation means and a button top), wherein the security switch is mounted in a housing wall 31 in a mounting opening by means of fixing means (screw ring 34). The actuation means (plunger 12) is designed so as to actuate contact elements of a switch module 18 upon actuation into the switch position. In security switches, the problem is known that a defective assembly of switch top and switch module or an unreliable separation between switch top and switch module cannot be identified from the outside, and the desired security shutdown does not function. The switch module 18 is therefore extended by a signalling switch block 20 that contains contact elements located in the signalling flow path, wherein, in the assembly state of the security switch, the signalling switch block is subjected to an actuation pin 46 that is rigidly arranged thereon. If the assembly state is undone or changed, the actuation pin disengages from the signalling switch block 20 and the signalling flow path 42 opens. The actuation pin and the signalling switch block are located outside the actuation region 100 of the actuation means (plunger 12) of the security switch.