PURPOSE: To accurately quantify the specific component in a fluid sample with good reproducibility by a method wherein a carrier is immersed in an antibody (antigen) solution to be allowed to stand and the solution is fluidized to manufacture an immobilizing carrier.

CONSTITUTION: A carrier to which an antibody (or antigen) is physically and/or chemically bonded is pref. porous and, as the material thereof, diatomaceous earth, titanium dioxide or a synthetic resin such as polystyrene is designated and said carrier pref. has a granular (bead like) shape. For example, a mesh-like container 3 having legs in which polyethylene beads 2 are received is inserted in a container 1 in which a solution of an antibody or an antigen is received and the beads 2 are immersed in the solution. A magnetic stirrer 3 is rotated in this state and the antibody or antigen solution is fluidized in a stationary state imparting no rotatory power to the beads 2 to uniformly bond the antibody or antigen to the beads 2.