Biological substance detection method

A method of specifically detecting a substance to be detected in a pathological section, the method comprising:

• immunostaining the pathological section with a fluorescent label;
• staining the pathological section with a staining reagent;
• observing morphology of the pathological section;
• and
• detecting the substance to be detected in the pathological section by irradiating the stained pathological section with excitation light and detecting fluorescence emitted therefrom, wherein
• in the immunostaining of the pathological section, a fluorescent nanoparticle-containing particle comprising an organic or inorganic material particle containing a fluorescent nanoparticle comprising phosphor or a semiconductor and having an excitation wavelength region different from an excitation wavelength region of the staining reagent is used as the fluorescent label, and
• the stained pathological section is not irradiated with excitation light having the excitation wavelength region of the staining reagent.