Provided is a structure capable of detecting near-infrared light with good sensitivity. Also provided are a composition for forming a near-infrared transmitting filter layer used in the structure and an optical sensor capable of detecting near-infrared light with good sensitivity. This structure 101 has a support 1, a partition wall 2 provided on the support 1, and a near-infrared transmitting filter layer 11 that shields visible light and transmits at least a portion of near-infrared light, provided in a region partitioned by the partition wall 2, in which the refractive index of the partition wall 2 is smaller than the refractive index of the near-infrared transmitting filter layer 11 at at least a portion of the wavelengths of the near-infrared light transmitted by the near-infrared transmitting filter layer 11.