PUMP

PROBLEM TO BE SOLVED: To provide a pump free from the occurrence of liquid dripping even in the case of increasing the internal pressure of a vessel with the increase of the temperature of an environment where the pump is placed. SOLUTION: An upper cap 34 for regulating the top dead center position of a piston 37 by abutting on a stem 36 is provided inside an accumulator 31, a communication hole 43 communicating with the inside of the vessel is formed in an accumulator chamber 31a above the piston 37 and a slit 44 communicating with the outside through a sliding gap (d) between the stem 36 and the upper cap 34 is formed in the contact part of the upper cap 34 with the stem 36. As a result, the increase of the inner pressure of the vessel with the increase of the temperature is communicated with the outside of the vessel through the communicating hole 43 in the accumulator chamber 31a, the slit 44 and the sliding gap (d) to prevent the pressurizing of the liquid content to prevent the occurrence of the liquid dripping.