A photodetection device 10 is provided wherein a condenser lens 12 is arranged in front of a photodetection element 11. This photodetection device is of high photodetection angular efficiency with a constant photodetection e.m.f. over a prescribed region, of high photodetection angular efficiency and does not pick up optical interference. By forming condenser lens 12 as a non-spherical lens that concentrates light onto a single point of convergence C without spherical aberration and moving the photodetection element 11 further towards lens 12 than the point of convergence C, it is arranged that light that has passed through condenser lens 12 is received over the entire region of the photodetection surface of photodetection element 11 and also that all of the light that is incident onto condenser lens 12 inclined at a prescribed angle is received by the photodetection surface.