PURPOSE: To enlarge pumping capacity and prevent liquid leakage and dropping from a pump by attaching a movable rod accompaniedly to a piston, providing their upper engaging part with a seal part, abuting the lower end of the movable rod onto an intake valve when the piston has attained its bottom dead center, and providing a spring between the intake valve and the piston.

CONSTITUTION: A movable rod 15 forms a seal part 18 by abuting an engaging cylindrical part 16 on a piston 7, and the bottom of a valve cylinder 1 is provided with a seat-shaped intake valve 24, and a spring 21 is provided between the intake valve 24 and the piston 7. This constitution can enlarge puming capacity, and makes separate liquid feeding possible for the possible use of proper liquid quantity without hand-manipulation. When the piston 7 approaches to a bottom dead center, the spring 21 is shortened to bring the lower end 15a of the movable rod 15 into contact with the intake valve 24 for checking the opening of the valve 24. The leakage of substance in the pump can be therefore prevented. When force to press the piston 7 downward is released, the spring 21 presses the piston 7 upward. Thus the substance in a piston pipe 10 and a discharge pipe 23 can be drawn into a valve chamber 20 to prevent liquid dropping from a discharge port 23a.