To provide a portable electric circular saw capable of warning an operator that cutting chips invade between a saw blade cover and a protruding section to prohibit smooth rotation of the saw blade cover before the saw blade cover is broken.

This circular saw is provided with a sleeve 4 having a shape of covering the outer periphery of the protruding section 2 between the protruding section 2 and the saw blade cover 1, and a detector for detecting the rotation of the sleeve 4.