PROBLEM TO BE SOLVED: To solve a problem in which, when optical characteristics of a measuring object in a cell are measured, a photoelastic effect of an entrance window and an emission window as optical windows of the cell reduces accuracy in measuring original optical characteristics of the measuring object.SOLUTION: An optical characteristics measuring method includes the steps of: arranging a measuring object in a cell; measuring a Mueller matrix of a system including a window from deflected incident light and emission light obtained through an emission window by radiating the incident light to the measuring object through an entrance window of the cell; acquiring a birefringence phase difference and a main axis azimuth of the entrance window and the emission window from the measured Mueller matrix of the system including the window; acquiring Mueller matrices of the entrance window and the emission window; acquiring a Mueller matrix of the measuring object; and acquiring Ψ indicating an amplitude rat
