The present invention addresses the problem of providing a method for distinguishing between prostate carcinoma and benign prostatic hyperplasia with high sensitivity and good reproducibility using an analyte sample in a small amount. The method for distinguishing between prostate carcinoma and benign prostatic hyperplasia according to the present invention, which is a solution for the problem, is as follows: an analyte sample containing a prostate-specific antigen (PSA) is brought into contact with a carrier having an anti-free PSA antibody immobilized thereon, thereby causing the binding of a free PSA to the anti-free PSA antibody immobilized on the carrier; the carrier in which the free PSA has been bound to the immobilized anti-free PSA antibody is brought into contact with a monoclonal antibody capable of specifically recognizing a sugar chain in which a terminal sialic acid residue is bound to galactose via an alpha(2,3) bond, thereby causing the binding of the monoclonal antibody capable of specifically recognizing the sugar chain in which the terminal sialic acid residue has been bound to galactose via an alpha(2,3) bond to the free PSA that has been bound to the anti-free PSA antibody immobilized on the carrier; the amount of the free PSA that has an N-type sugar chain in which the terminal sialic acid residue has been bound to galactose via an alpha(2,3) bond is measured; and subsequently the amount measured in the proceeding step is compared with a preset cut-off value for prostate carcinoma and benign prostatic hyperplasia. When the measured amount is larger than the cut-off value, it is determined that prostate carcinoma is developed or the probability of prostate carcinoma is high. When the measured amount is smaller than the cut-off value, it is determined that benign prostatic hyperplasia is developed or the probability of benign prostatic hyperplasia is high.