To provide a bench circular saw machine capable of easily acquiring function of a stiffening plate when required, improving usability and not causing a trouble of storing the stiffening plate and danger of losing it.

An auxiliary base 25 free to operate to move from a lowering position where an upper surface becomes as high as an upper surface of a base 2 to a projecting position where the upper surface becomes higher than the upper surface of the base 2 and a stopper mechanism 28 free to hold the auxiliary base 25 at the projecting position are provided on the base 2 of a sliding circular saw 1.