Apparatus for separation, washing and mixing of magnetic particles in at least one reaction cup, adapted to be used in an immunoanalyzer system, said at least one reaction cup containing nanometric magnetic particles (beads) binding immuno-complex antibody, antigen molecules, and liquid, comprising: - a supporting dial mechanism (11) in the form of a rotating carousel, comprising an upper side with a number of holes adapted to host a corresponding number of said at least one reaction cup (1) in substantially vertical positions, and a lower side comprising a number of guide grooves (2) radially behind corresponding holes of the upper side, - a number of magnet mechanisms (30) adapted to be inserted in corresponding ones of said guide grooves (2) and to slide therein, so as to radially approach to or depart from the side external surface of corresponding ones of said at least one reaction cup (1); - at least one washing mechanism (40) firmly installed around said supporting dial mechanism (11), and comprising a washing needle (44) able to move vertically in and out said at least one reagent cup for charging or extracting said liquid; - at least one mixing mechanism (70) firmly installed behind and aside said supporting dial mechanism (11), adapted to shake (stir) at least one reaction cup so as to mix the content of the reaction cup.