Abstract: A circular saw includes a machine housing disposed on a base to cooperatively define a working space therebetween, and a saw blade driven by a driving motor so as to rotate through a drive transmitting device accommodated in the machine housing. The device includes a first input shaft driven by the motor and having a first leading wheel mounted thereon, a middle shaft having a first trailing wheel and a second leading wheel mounted thereon to be rotated with the first input shaft through a first transmitting belt, a second input shaft having a second trailing wheel mounted thereon to be rotated with the middle shaft through a second transmitting belt, and a gear reduction device disposed to couple the second input shaft to the saw blade.