To obtain a structure capable of safely and comfortably using a motor-operated circular saw to obviate the situation in which a member to be used hits a slide frame cover of a lower portion of the motor-operated circular saw during using, to cause an inferior flow and temporary stop.

The body of a motor-operated circular saw 11 is integrally formed with an upper portion 12 of a circular type frame 12 covering circular saws. However, a slide frame cover of a lower portion slides by being pressed by a member 25 to be used when cutting it. However, every one of the conventional circular saws stops temporarily in the middle, and it is difficult to use, involving a danger. In order to solve this problem, a roller 16 is attached to the tip of the slide frame cover of the lower portion, to thereby realize the circular saw capable of causing the roller 16 to rotate when the member 25 to be used touches on the roller 16, and securing the safety of an operator without stopping the slide frame cover of the lower portion, in a smooth and comfortable operation state.