An electromagnetic wave sensor cover configured to be employed in an electromagnetic wave sensor including a transmitting portion that transmits an electromagnetic wave in form of infrared rays and a receiving portion that receives the electromagnetic wave the electromagnetic wave sensor cover comprising a cover body (20; 34; 41; 42) configured to cover the transmitting portion and the receiving portion from a front in a transmission direction of the electromagnetic wave from the transmitting portion, wherein the cover body (20; 34; 41; 42) includes: a base layer made of synthetic resin and permitting passage of the electromagnetic wave; a metal oxide layer permitting passage of the electromagnetic wave and being conductive; a low refractive index layer permitting passage of the electromagnetic wave; and two electrodes disposed in contact with the metal oxide layer to energize the metal oxide layer so that the metal oxide layer generates heat, the base layer includes a front surface and a rear surface in the transmission direction, the metal oxide layer and the low refractive index layer are laminated adjacent to each other in the transmission direction, a laminate of the metal oxide layer and the low refractive index layer is laminated on the rear surface of the base layer , and the low refractive index layer is laminated adjacent to a rear surface of the metal oxide layer in the transmission direction and made of material that has a lower refractive index than material of the metal oxide layer so that a reflected wave of the electromagnetic wave reflected on a boundary of an air layer and the low refractive index layer and a reflected wave of the electromagnetic wave reflected on a boundary of the low refractive index layer and the metal oxide layer interfere with each other and weaken each other. and a receiving portion that receives the electromagnetic wave the electromagnetic wave sensor cover comprising a cover body (20; 34; 41; 42) configured to cover the transmitting portion and the receiving portion from a front in a transmission direction of the electromagnetic wave from the transmitting portion, wherein the cover body (20; 34; 41; 42) includes: a base layer made of synthetic resin and permitting passage of the electromagnetic wave; a metal oxide layer permitting passage of the electromagnetic wave and being conductive; a low refractive index layer permitting passage of the electromagnetic wave; and two electrodes disposed in contact with the metal oxide layer to energize the metal oxide layer so that the metal oxide layer generates heat, a base layer made of synthetic resin and permitting passage of the electromagnetic wave; a metal oxide layer permitting passage of the electromagnetic wave and being conductive; a low refractive index layer permitting passage of the electromagnetic wave; and two electrodes disposed in contact with the metal oxide layer to energize the metal oxide layer so that the metal oxide layer generates heat, the base layer includes a front surface and a rear surface in the transmission direction, the metal oxide layer and the low refractive index layer are laminated adjacent to each other in the transmission direction, a laminate of the metal oxide layer and the low refractive index layer is laminated on the rear surface of the base layer , and the low refractive index layer is laminated adjacent to a rear surface of the metal oxide layer in the transmission direction and made of material that has a lower refractive index than material of the metal oxide layer so that a reflected wave of the electromagnetic wave reflected on a boundary of an air layer and the low refractive index layer and a reflected wave of the electromagnetic wave reflected on a boundary of the low refractive index layer and the metal oxide layer interfere with each other and weaken each other. <EOS>