Abstract: [Problem] To provide a light-concentrating mechanism that is suitable for photovoltaic power generation. [Solution] This light-concentrating mechanism comprises an angle selective reflection means that reflects light having an incident angle of at least a first threshold angle and transmits at least some of the light having an incident angle smaller than the first threshold angle, and an angle-increase reflection means that reflects incident light at an angle greater than the incident angle of said light, the two means being arranged so as to have a gap therebetween.