PURPOSE: To obtain a diaphragm pump which is able to obtain a high discharge pressure, by arranging so that a fluid which has been pressurized at the 1st pump chamber may be sent out after further having been pressurized at the 2nd pump chamber whose capacity is smaller than that of the 1st pump chamber.

CONSTITUTION: When a motor 1 is rotated, a lever 13 conducts swinging with a shaft 14 as a center, and when the lever 13 is turned clockwise, it presses pushingly a diaphragm 7 and the inner capacity of a pump chamber 9 is made to be smaller, thus the pressure of a fluid within the pump chamber 9 becomes higher due to being compressed, and the fluid flows into a pump chamber 10 by opening a connecting valve 9. At this time, the inner capacity of the pump chamber 10 is made to be larger by means of the diaphragm 8 due to the turning movement of the lever 13, thus the fluid makes a sure inflow. When the motor 1 rotates further, the turning movement direction of the lever 13 is reversed, thus a suction stroke at which the fluid makes inflow through a suction opening 6 by opening a suction valve 4, is brought on the pump chamber 9 side, and conversely, on the pump chamber 10 side, a high pressure fluid which is obtained by pressurizing further the fluid that has been pressurized at the pump chamber 9, is sent out through a discharge opening 5 via a discharge valve 12.