PURPOSE: To prevent the deviation in the quantity of rinsing liquid due to excessive drop of the liquid from a distribution needle by arranging the distribution needles and distributor so as to be connected to a recovery tank as soon as the supply of the rinsing liquid to a test tube is shut off.

CONSTITUTION: A vacuum pump 24 is always kept running. As a control valve 6 is energized with a pressure pump 15 in operation, a rinsing liquid supply pipe 12 is communicated between the side 12b of a rinsing liquid tank and the side 12a of a contributor while the communication between a bypass pipe 5 and the pipe 12 is cut and the rinsing liquid in a tank 13 is distributed to a test tube (a) from distribution needle 1. Under such a condition, with the cutting of the energization thereof 6, a pipe 12a is connected to a bypass pipe 5 and insulated from a pipe 12b to stop the supply of liquid from the tank 13 while the rinsing liquid in the distributor 10 and the distribution needles 1 is recovered to a recovery tank 22. Then, a suction needle 2 is put into the test tube (a) to recover the rinsing liquid into a recovery tank 22. Thus, the deviation in the rinsing liquid quantity can be prevented with a simple construction.