Abstract: A method for examining cancer cells by which examination of cancer cells may be carried out simply and efficiently without using an expensive apparatus, and a reagent therefor are disclosed. In the method for examining cancer cells according to the present invention, cancer cells separated from the body, which cells express SF-25 antigen on their surfaces, are bound to magnetic beads utilizing antigen-antibody reaction between the cancer cells and an anti-SF-25 antibody or antigen-binding fragment thereof, and then the magnetic beads are collected by magnetic force, and the cancer cells bound to the magnetic beads are examined.