A pedal-driven exercise machine is designed for an exerciser in a seated position to do pedaling. The pedal-driven exercise machine is equipped with a main body portion, a crank unit that is rotatably supported by the main body portion, a pedal unit that is rotatably supported by the crank unit, and a foot space securing unit that secures a foot space at a foot of the exerciser by retreating the pedal unit from the foot of the exerciser when the pedal-driven exercise machine is out of use.