Abstract: A photometrical apparatus has a first light receiving element, and a second light receiving element less sensitive to temperature and other environmental influences than said first light receiving element whereby a value Pm of measured quantity of light from the subject is calculated from the following formula ##EQU1## Pr designates a quantity of light from a standard light source, Dr and Dm designate outputs of the first light receiving element generated by the light from the standard light source and the subject, Dpo and Dpt designate outputs of the first light receiving element generated by the light from the reference light source and the subject, and Dso and Dst designate outputs of the second light receiving element generated by the light from the reference light source and the subject.