Raman spectroscopy is widely used to analyze the crystallographic states of materials surfaces and thin films. Raman shift is informative to analyze stresses or defective bonds on surfaces. However, because of the instability of room temperature, the overall precision of the measured Raman shift is not always satisfied in a commercial Raman spectroscopy system. In this report, we describe how room temperature affects the Raman shift in a spectrometer with large dispersion. The temperature dependence of the system was predicted theoretically by a difference in thermal expansion coefficients between an optical bench and diffraction grating, which indicates that a linear shift of wavenumber is effective to cancel the apparent temperature shift. As an example of high-resolution measurements, strain-induced Raman shift of diamond was calibrated by the reference emission line of Hg to detect a shift of less than the resolution: 0.3 cm-1. Furthermore, laser-induced heating of Si surface was evaluated only by calibration based on room temperature without using any reference emission lines.