A circuit breaker includes a latch including a switching mechanism for opening and closing a switching contact operatively connected to a tensioning element, and an unlatching mechanism by which, on the basis of a tripping signal, the tensioning element can be changed from a tensioned to an at least largely untensioned state, thereby opening the switching contact. In an embodiment, the tensioning element is indirectly linked to a tensioning lever having a locating surface on which a locking pawl of the unlatching mechanism bears in the tensioned state of the tensioning element. The locating surface is curved in the direction of the locking pawl and is movably disposed relative to the tensioning lever.