An optical sensor system includes an optical sensor head having a light-emitting device and a detector which detects light emitted from the light-emitting device, and a calculator circuit. The light-emitting device includes a resonator which includes a first reflective surface, a second reflective surface facing the first reflective surface, and a waveguide provided between the first reflective surface and the second reflective surface. At least one metal microparticle capable of exciting surface plasmon is formed on the first reflective surface. The calculator circuit calculates an environment parameter at the first reflective surface on the basis of a detected value from the detector.