An infrared detector includes a substrate, a light blocking layer on the substrate, a lower electrode on the light blocking layer, the lower electrode electrically connected to the light blocking layer, a lower insulating layer on the light blocking layer, a first semiconductor layer on the lower insulating layer, a first source electrode and a first drain electrode on the first semiconductor layer, an upper insulating layer on the first semiconductor layer, and a first gate electrode on the upper insulating layer, the first gate electrode electrically connected to the lower electrode, where the first semiconductor layer includes a zinc and a nitrogen, and the first semiconductor layer is configured to generate electric charges by reacting with an infrared ray.