This battery-embedded device comprises: a substrate having wiring lines; a coil fixed to the substrate; a battery fixed to the substrate; and a first temperature detection element that is arranged on the substrate and that detects the temperature of the battery. The occupancy rate of the wiring lines in a first region of the substrate immediately below the first temperature detection element is lower than the occupancy rate of the wiring lines in a second region of the substrate other than the first region.
