The subject innovation relates to a portable electric saw to the saw blade is reciprocated by rotation force of the electric motor and more particularly relates to a portable electric saw. Object of the present invention is to provide a portable, a top round trip distance is increased by the improved cutting performance in portable electric saws while excellent low cost in order to solve the above problems. In order to achieve the above object, the subject innovation, in the electric saw using a rotational force of the electric motor, endless belt that rotates by the rotational force of the electric motor; One side is a radius of center curvature of the caterpillar belt in rotation with the endless belt, and the other side a linear motion curve, the straight portion of the endless belt as the endless belt rotates fitted on the side of the endless belt the connecting member is provided with a protrusion to the rotational motion to the position; And coupled to the projection it provides a portable electric saw comprises a saw blade which reciprocates with the protrusion. The subject innovation is an effect that improves the portability, and there is an effect to provide a superior economical chainsaw to be manufactured at a low cost. Portable electric saw, caterpillar belt