PURPOSE: To spare the rinsing operations thereby to improve the analyzing operations by equipping a suction pump with an automatic rinsing device which is enabled to accomplish the automatic operations from the measurement and rinsing merely by the selecting and switching operation of a direction switching valve.

CONSTITUTION: A direction switching valve 2 attached to a syringe 1 has it one port connected with the pipe of a flow cell 5 and its other port connected with the common connecting port of a check valve 21. This check valve 21 has its suction passage 23 connected with a direction switching valve 22 for selecting the rinsing liquid, which is further connected with the pipes 24 and 25 for introducing the rinsing water and the washing agent so that either of them can be selected. These are selectively switched by using the two valves 2 and 22 as well as the checking operation of the valve 21 to effect the pumping operations of the syringe 1. Thus, the color comparison analysis of the reacting sample and the rinsing operations of the passage can be accomplished. As a result, it is possible to improve the analyzing operations while sparing the rinsing operations.