A post-processing apparatus includes: a cutter that cuts a transported sheet; a waste bin that stores a cutting waste generated by a cutting operation of the cutter and falling from the cutter; a sensor that detects the cutting waste at a predetermined position in a depth direction in the waste bin; and a hardware processor that controls the cutting operation of the cutter according to a cutting mode, sets a predetermined value according to the cutting mode when the sensor detects the cutting waste, counts the number of times of cutting by the cutter after the sensor starts to detect the cutting waste, and detects that the waste bin is full when the counted number of times of cutting reaches the predetermined value.