To provide a glucose sensor chip having a sensing film with high measuring sensitivity.

The glucose sensor chip includes a light waveguide layer 3 containing a pair of the gratings 4 provided on the main surface of a substrate 2 in a mutually spaced-apart state and the sensing film 5 provided to the part of the light waveguide layer 3 across a pair of the gratings 4. The sensing film 5 is formed of a film forming high-molecular compound a crosslinkable high-molecular compound and a porous low-molecular compound. A colorant, first enzyme for oxidizing or reducing glucose and second enzyme, which reacts with the product of the first enzyme to produce a substance for developing the colorant, are held in the sensing film.