A pump comprising: a housing (11, 12) that has a compression chamber for pressurizing fluid, the housing (11, 12) further having a cylindrical portion having a fluid passage (20, 21, 22, 31, 41) for guiding fluid into the compression chamber, a valve that is located midway through the fluid passage (20, 21, 22, 31, 41), the valve being adapted to communicate or to block the fluid passage (20, 21, 22, 31, 41), a valve body accommodated in the cylindrical portion; a solenoid actuator that is located on a substantially opposite side of the compression chamber with respect to the valve, the solenoid actuator being adapted to operate the valve; characterized in that the pump further comprises: a regulating member (130, 131, 140, 141, 142, 143, 144, 145, 146, 147) that is located between the valve and the solenoid actuator, the regulating member (130, 131, 140, 141, 142, 143, 144, 145, 146, 147) including an engaging member (140, 141, 142, 143, 144, 145, 146, 147), which is engaged with an outer wall of the valve body and an inner wall of the housing (11, 12), and a seal member (130, 131) arranged between the outer wall of the valve body and the inner wall of the housing (11, 12) and sealing the valve body and the housing (11, 12) therebetween, wherein the valve body is biased by resilience toward the solenoid actuator. a housing (11, 12) that has a compression chamber for pressurizing fluid, the housing (11, 12) further having a cylindrical portion having a fluid passage (20, 21, 22, 31, 41) for guiding fluid into the compression chamber, a valve that is located midway through the fluid passage (20, 21, 22, 31, 41), the valve being adapted to communicate or to block the fluid passage (20, 21, 22, 31, 41), a valve body accommodated in the cylindrical portion; a solenoid actuator that is located on a substantially opposite side of the compression chamber with respect to the valve, the solenoid actuator being adapted to operate the valve; characterized in that the pump further comprises: a regulating member (130, 131, 140, 141, 142, 143, 144, 145, 146, 147) that is located between the valve and the solenoid actuator, the regulating member (130, 131, 140, 141, 142, 143, 144, 145, 146, 147) including an engaging member (140, 141, 142, 143, 144, 145, 146, 147), which is engaged with an outer wall of the valve body and an inner wall of the housing (11, 12), and a seal member (130, 131) arranged between the outer wall of the valve body and the inner wall of the housing (11, 12) and sealing the valve body and the housing (11, 12) therebetween, wherein the valve body is biased by resilience toward the solenoid actuator. a regulating member (130, 131, 140, 141, 142, 143, 144, 145, 146, 147) that is located between the valve and the solenoid actuator, the regulating member (130, 131, 140, 141, 142, 143, 144, 145, 146, 147) including an engaging member (140, 141, 142, 143, 144, 145, 146, 147), which is engaged with an outer wall of the valve body and an inner wall of the housing (11, 12), and a seal member (130, 131) arranged between the outer wall of the valve body and the inner wall of the housing (11, 12) and sealing the valve body and the housing (11, 12) therebetween, an engaging member (140, 141, 142, 143, 144, 145, 146, 147), which is engaged with an outer wall of the valve body and an inner wall of the housing (11, 12), and a seal member (130, 131) arranged between the outer wall of the valve body and the inner wall of the housing (11, 12) and sealing the valve body and the housing (11, 12) therebetween, wherein the valve body is biased by resilience toward the solenoid actuator.