The invention relates to a desk circular saw machine. The begone stopper member is pressed on the side of the safety cup to form moving resistance, therefore the safety cup maybe not rotate smoothly, wherein the stopper member is used to locking the safety up which rotates relative to cutter shield to switch the cutter at the dead point on the main body of cutting-off machine to make it not open.In the said invention, even the stopper member is bunted with the side, the safety cup will rotate smoothly. The stopper member (41) is separated into stopper supporter (42) and stopper main body (43), and a second energizing unit (43b) is mounted betweent the two parts, to make the energized force on the restrict part (43a) of the stopper main body (43) less than the first energized force of the dead point locking mechanism.