Provided is a spectral filter including a first unit filter having a first center wavelength in a first wavelength range, and a second unit filter having a second center wavelength in a second wavelength range, wherein the first unit filter includes two first metal reflective layers provided spaced apart from each other and including a first metal, and a first cavity provided between the two first metal reflective layers, and wherein the second unit filter includes two second metal reflective layers provided spaced apart from each other and including a second metal different from the first metal, and a second cavity provided between the two second metal reflective layers.