PURPOSE: To prevent the bend and break of a probe by controlling the move and stop of a suction pipe formed of an electric conductor by means of a member of an electric conductor provided with a through hole allowing the movement of the suction pipe, and aranged above a liquid container.

CONSTITUTION: After being lowered into a sample container 1 by a probe moving mechanism 4 according to an instruction from a microcomputer, a liquid suction pipe 2 retained by a retaining arm 11 is raised again and moved to just above a reaction vessel and discharges a sample into the vessel. A guide cover 6 of an electric conductor is fixed to a sample table, and when the sample container stops at a prescribed place, the liquid suction pipe 2 of an electric conductor is inserted into the container 1 through the opening of the guide cover 6. When the suction pipe touches the cover 6 on the occasion, continuity is generated between them, and thereby a contact detecting circuit 7 is made to operate to make a computer give an instruction to stop the lowering movement of a probe 2 through the moving mechanism 4. Thus, the bend and break, etc. of the probe 2 are avoided.