An electromagnetic wave detector including a first electromagnetic wave sensor including a light reception unit held in midair above a substrate by a support leg and a second electromagnetic wave sensor including a light reception unit held in midair above the substrate by a support leg having same structure as the support leg of the first electromagnetic wave sensor and provided adjacent to the first electromagnetic wave sensor. The light reception unit of the first electromagnetic wave sensor includes a reflective film, the light reception unit of the second electromagnetic wave sensor includes an electromagnetic wave absorption body for detecting light of a prescribed wavelength band or a prescribed polarization, and the difference between the output of the second electromagnetic wave sensor and the first electromagnetic wave sensor is output.