To provide a pump which has satisfactory pulsation absorbing performance and can be formed in a compact size.

This pump is provided with a liquid discharge chamber 27 and two or more pulsation absorbing air chambers 29a, 29b communicated with the liquid discharge chamber 27. At least a part of the liquid discharge chamber 27 and at least a part of at least one air chamber 29a of two or more air chambers 29a, 29b are formed by the same member 19. Two or more air chambers 29a, 29b respectively exhibit pulsation absorbing action, therefore, pulsation absorbing performance as a whole of the pump is improved. In addition, since at least a part of the liquid discharge chamber 27 and at least a part of at least one air chamber 29a of two or more air chambers 29a, 29b are formed by the same member 19, the pump can be formed in the compact size.