To generate power for night lighting of a bicycle not to charge a load to a rider at night.

When a person treads the left pedal of the bicycle, the saddle 3 mounted to the bicycle is pressed down left by pressure 1 applied to the left of the saddle 3 due to the weight movement of the person. The movement of the saddle 3 causes a left-side piston shaft 4 to move, and the movement of the piston shaft 4 causes a rotary shaft 12 to start rotating. Next, when the person treads the right pedal of the bicycle, the saddle 3 mounted to the bicycle is pressed down right by pressure 2 applied to the right of the saddle 3 due to the weight movement of the person. The movement of the saddle 3 causes a right-side piston shaft 5 to move, and the movement of the piston shaft 5 causes the rotary shaft 12 to start rotating. The rotation of the rotary shaft 12 is transmitted to a gear 6 mounted to the rotary shaft, further a gear 7 mounted to a power generator is moved, and power generation is performed by the power generator 8.