To allow accurate return to an original reference position with easy operation after fine-adjustment, considering that a table-top circular sawing machine has a fine-adjustment function for a positioning mechanism to position a rotary table but a conventional fine-adjustment mechanism has troublesome operation and poor user-friendliness because of impossible return to the original reference position.

A reference fixing pin 50 is provided on a supporting member 41 which supports a positioning pin 33 to be inserted into a positioning hole 2c of a base 2 for positioning the rotary table 3, movably in the direction of fine-adjustment. The reference fixing pin 50 is inserted into a reference fixing hole 51 for returning the supporting member 41 to the reference position.