To provide an easily attachable small photometry device which accurately measures a received light quantity.

The photometry device is provided with a light-shielding cap 45 which integrally connect an element cover 43, a first light-shielding member 51 and a second light-shielding member 52 by means of a coupling part 53. The element cover 43 closely covers the front and side surfaces of a light receiving element 42 and has an incidence opening on the front surface to make incident part of external light on the light receiving element 42 through a light receiving window 9. The first light shielding member 51 having elasticity is placed between the back surface of the front cover 24 and the element cover 43. Where the incidence opening 47 is opened, the rear edge of the first light shielding member 51 contacts the front surface of the element cover 43, and the front edge contacts the back surface of the front cover 24. The second light shielding member 52 having elasticity covers the light receiving element 42 closely from the back surface side and has a terminal insertion hole 52a to insert a terminal 42b projecting from the rear end of the light receiving element 42. The element cover 43 is attached to a second substrate 39 to position the light receiving element 42 to the surface of the second substrate 39, thereby light passing through the incidence opening 47 is uniquely made incident on the light receiving element 42.