The present invention provides a small sized wide wave-range spectroscope with a simple structure which requires a short time to measure light for measurement over a wide wavelength spectrum. The small sized wide wave-range spectroscope has a collimator (43) for changing light for measurement (L) transmitted through a slit (41) into collimated light (L0), a plurality of diffraction gratings (44a, 44b) with different grating constants d supported rotatably around a rotational axis in parallel with the incident slit (41) and disposed side by side in the direction of the rotational axis in the optical path of the collimated light (L0), and a diffracted-light focusing members (45a, 45b) for focusing a plurality of diffracted light rays (L1 to L4) provided by the plurality of diffraction gratings (44a, 44b) by which the collimated light (L0) is diffracted, each of the diffracted-light focusing members (45a, 45b) being provided in association with each of the plurality of diffraction gratings (44a, 44b).