PURPOSE: To provide a simple and quick single process assay for detecting a specific antibody in a sample using a two zone chromatograph comprising a chromatograph matrix including a detection zone and a capturing zone in the downstream thereof.

CONSTITUTION: The chromatograph matrix 1 of a two zone chromatograph includes a detection zone 2 and a capturing zone 3 in the downstream thereof. The detection zone 2 comprises detection particles coated with an antigen or an equivalent while the capturing zone 3 comprises an antigen or an equivalent bonded to the chromatograph matrix 1. In the assay, a sample containing a specific antibody is mounted on the apparatus in the upstream of the detection zone 2. The specific antibody is bonded, at first, to the detection zone particle and the complex is bonded to the capturing zone 3 where a detection signal is read out. A granular substance is detected and one useful particle is a suck containing a pigment or other coloring substance as a read out substance.