To improve a shape of a release lever by which a reverse spring is operated in order to stabilize an operation current value of a thermal overload relay.

The thermal overload relay has an outer shell case in which a main bimetal bent and displaced by conduction of an overcurrent, a shifter displaced responding to the bending of the main bimetal, a release lever rotated by the displacement of the shifter through a support shaft, and a contact reversing mechanism driven by the release lever are internally installed. The contact reversing mechanism comprises an assembly of a reverse spring linked with the release lever, a slider coupled to the reverse spring, an output contact which performs open/close operation in response to the movement of the slider, and a reset button. A press part of the release lever, which presses an action part of the reverse spring in order to trip the reverse spring, is made to have a line contract structure against the axial direction of the support shaft.