PROBLEM TO BE SOLVED: To provide a detection liquid which can simply and rapidly determine the presence or absence of cancer in a tissue sampled from an organism, and to provide a cancer detection method.SOLUTION: The invention provides a detection liquid in which a particulate marker is dispersed into an aqueous medium, a polymer and a differential substance are contained, a mean particle diameter is from 1 nm to 100 &mu；m, a main skeleton is a styrene polymer in which the polymer is copolymerized with a substituted styrene containing a lectin residue, and the ratio of the lectin in the polymer is 0.1-0.7 mass%. The differential substance is a fluorescent substance. The invention also provides a cancer detection method which can readily determine cancer cells by applying the detection liquid to a tissue sampled from an organism to bind cancer cells to a particulate marker.
