reaction container 1 and then driven by a pump 15 to suck the liquid in the reaction container 1 such that all the liquid phase is substantially completely removed therefrom after the liquid phase has been removed the nozzle 7 is raised above the reaction container 1 the waste liquid thus sucked from the reaction container 1 is collected in a tank 17 the operations of the up and down mechanism 13 and the pump 15 are controlled by the controller 5 a sequence of steps at the positions a e are performed for the separation of the bound phase and the free phase in the reactive liquid in the stations 40 42 and also for the separation of the solid supports dispersed in the washing liquid from a waste liquid during the washing operation in the station 41 shown in fig1 the second and subsequent washing operations in the washing stations now shown in fig1 are also performed in the above described manner on the reaction container positioned at the positions a e in order to elude substances unspecifically adsorbed on the solid supports magnetic micro particles which were not completely removed by the first washing operation into the washing liquid for removing such substances next the flocculation action.