An optical waveguide type biochemical sensor chip includes a light beam transmittable substrate having at least a first optical element that allows light beam to be impinged to the inside and a second optical element that emits light beam from the inside, an optical waveguide layer that is formed on a main surface of the substrate on which at least one of the first and second optical elements is formed, has a thickness of 3 to 300 .mu.m and is made of a polymer resin material having a higher refractive index than that of the substrate material, and a sensing membrane that is formed on the optical waveguide layer and creates a reaction product having the ability of absorbing the light beam or an evanescent wave of the light beam in response to an introduced specimen.