An RGB filter for selectively transmitting light of wavelengths in a red zone, green zone, and blue zone by making use of respective plasmon resonance, comprising: a substrate; a light-shielding conductive layer on a surface of the substrate, said conductive layer being provided with a red zone region, a green zone region, and a blue zone region, each region having a plurality of square apertures surrounded by the conductive layer and arranged two-dimensionally periodic in the in-plane directions of the substrate; and a dielectric layer provided on the conductive layer and embedded in the apertures; wherein, in each of said regions, a ratio of a surface area of the conductive layer to a surface area of the substrate surface is within a range of equal to or greater than 36% and equal to or less than 74%, and a thickness of the conductive layer is within a range of equal to or greater than 10 nm and equal to or less than 200 nm; in the red zone region, a side length (141, 151) of the apertures is within a range of equal to or greater than 220 nm and equal to or less than 270 nm, an arrangement period (145, 155) of the apertures is within a range of equal to or greater than 310 nm and equal to or less than 450 nm, and a maximum value of a transmission spectrum is within a wavelength range of equal to or greater than 600 nm and equal to or less than 700 nm; in the green zone region, a side length (141, 151) of the apertures is within a range of equal to or greater than 180 nm and equal to or less than 220 nm, an arrangement period (145, 155) of the apertures is within a range of equal to or greater than 250 nm and equal to or less than 310 nm, and a maximum value of a transmission spectrum is within a wavelength range of equal to or greater than 500 nm and equal to or less than 600 nm; and in the blue zone region, a side length (141, 151) of the apertures is within a range of equal to or greater than 100 nm and equal to or less than 180 nm, an arrangement period (145, 155) of the apertures is within a range of equal to or greater than 170 nm and equal to or less than 250 nm, and a maximum value of a transmission spectrum is within a wavelength range of equal to or greater than 400 nm and equal to or less than 500 nm. a substrate; a light-shielding conductive layer on a surface of the substrate, said conductive layer being provided with a red zone region, a green zone region, and a blue zone region, each region having a plurality of square apertures surrounded by the conductive layer and arranged two-dimensionally periodic in the in-plane directions of the substrate; and a dielectric layer provided on the conductive layer and embedded in the apertures; wherein, in each of said regions, a ratio of a surface area of the conductive layer to a surface area of the substrate surface is within a range of equal to or greater than 36% and equal to or less than 74%, and a thickness of the conductive layer is within a range of equal to or greater than 10 nm and equal to or less than 200 nm; in the red zone region, a side length (141, 151) of the apertures is within a range of equal to or greater than 220 nm and equal to or less than 270 nm, an arrangement period (145, 155) of the apertures is within a range of equal to or greater than 310 nm and equal to or less than 450 nm, and a maximum value of a transmission spectrum is within a wavelength range of equal to or greater than 600 nm and equal to or less than 700 nm; in the green zone region, a side length (141, 151) of the apertures is within a range of equal to or greater than 180 nm and equal to or less than 220 nm, an arrangement period (145, 155) of the apertures is within a range of equal to or greater than 250 nm and equal to or less than 310 nm, and a maximum value of a transmission spectrum is within a wavelength range of equal to or greater than 500 nm and equal to or less than 600 nm; and in the blue zone region, a side length (141, 151) of the apertures is within a range of equal to or greater than 100 nm and equal to or less than 180 nm, an arrangement period (145, 155) of the apertures is within a range of equal to or greater than 170 nm and equal to or less than 250 nm, and a maximum value of a transmission spectrum is within a wavelength range of equal to or greater than 400 nm and equal to or less than 500 nm.