The amount of enzyme is determined by reacting an enzyme to be measured with a synthetic substrate having at least one structure to be specifically contacted with the enzyme and at least one spectral sensitizer structure, bringing either the reaction product having the spectral sensitizer structure or the unreacted synthetic substrate into contact with a silver halide emulsion layer, exposing the same to light of a spectral sensitizing wavelength region corresponding to the spectral sensitizer structure, developing the silver halide, and then measuring the optical density of developed silver and/or colored dye.