An infrared detector may include a substrate, a resonant unit spaced apart from the substrate, the resonant unit configured to generate heat by inducing resonance at a plurality of wavelengths of incident infrared light, a thermistor layer configured to support the resonant unit and be spaced apart from the resonant unit, the thermistor layer having a resistance value that varies according to the heat generated in the resonant unit, and a connection unit configured to support the thermistor layer such that the thermistor layer is spaced apart from the substrate and electrically connect the thermistor layer to the substrate.