There is disclosed a washing device for use with an automatic biochemical analyzer using reaction containers. The washing device comprises a sucking portion and a draining tube. When the sucking portion is advanced into any one reaction container placed in position and is set in a given position, a communication passage is created between the inner wall surface of the container and the outer wall surface of the sucking portion and between the bottom surface of the container and the bottom surface of the sucking portion. During draining, the container is depleted of wash liquid. Outside air flows from the communication passage into the container through its opening at the top end at a flow rate more than a given value. The air flow blows away the water droplets adhering to the inner wall surface of the container. The blown water droplets are urged downward toward the sucking port in the suction portion. Then, the water droplets are discharged into a waste tank through the draining tube. Thus, the water droplets can be easily and almost completely removed.