PURPOSE: To reduce exchange the number of parts due to defective machining, etc., to the minimum and reduce the cost by forming a plunger pump by mutually connecting respective pump units.

CONSTITUTION: A plunger pump 1 is formed with a front side pump unit 2 and a rear side pump unit 3. Respective housings of the front and rear side pump units 2, 3 are formed y front and rear side plunger storing units 4, 5 and pressure chambers 6, 7 having check valves 8, 9 for relatively dividing. Thereby, the plunger pump 1 can easily be assembled by piling up the front side plunger storing unit 4, the front side pressure chamber 6 having the check valve 8, the rear side plunger storing unit 5, the rear side pressure chamber 7 having the check valve and a cover 55 sequentially and securely fixing them by bolts 10.