To provide a bimetal type overcurrent breaker which has a structure in which the operating point of a bimetal can be easily set without needing a complicated structure or process for fine adjustment using such as a screw.

The overcurrent breaker includes a case; a first and second fixed terminals formed to protrude through the bottom of the case to the outside; a first and second fixed contacts connected to the first and second fixed terminals and set within the case; a bimetal formed in a curved shape allowing reversing movement, the bimetal having a support hole formed at the center and including a first movable contact contacting the first fixed contact and a second movable contact contacting the second fixed contact; a fixing plate which has an adjustment portion for supporting the center of the bimetal protruded thereon and fixes the bimetal to the case; a fixing implement which fixes the bimetal to the center of the fixing plate; and a cover which covers the upper surface of the case. The protruding height of the adjustment portion is minutely adjusted, whereby the operating point of the bimetal is adjusted.