PURPOSE: To wash a vessel in a short time by piercing the bottom of vessel with a washing pipe, holding the pierced part, and blowing a diluted liquid inside the vessel.

CONSTITUTION: A washing pipe 23 is moved to the first position, a cover 13 is opened, and a shielded vessel 33 in which a desired chemical substance is put is inserted in a chamber 11. Then the cover 13 is closed, a pinion shaft 26 is rotated, and the pipe 23 is lowered up to the second position. During falling of the pipe 23, a point end 28 pierces the upper surface of vessel 33, and penetrates a lower square corner positioned to block its inside and a flow channel 17. Thus, a content in the vessel 33 is discharged to the flow channel 17 through a groove 29 provided in the pipe 23. Then, a diluted liquid is blown from a plurality of nozzles 40 of the pipe 23, so that the inside of vessel 33 is washed and a chemical substance in a reservoir 18 is diluted. At the same time, the diluted liquid washes the inside of chamber 11 and the outside surface of vessel 33 through a blowing head 32.