An infrared circuit for a single battery and a remote controller using the same are provided. The single battery outputs a battery voltage. The infrared circuit comprises an IR LED circuit, an inductor and a microcontroller. The IR LED circuit is coupled between the battery voltage and a common voltage. The inductor is coupled between the battery voltage and the common voltage. The microcontroller has an I/O port coupled to the inductor and the IR LED circuit. When infrared rays are emitted, the microcontroller controls the battery voltage to charge the inductor through the I/O port, and a continuous current of the inductor forces the IR LED circuit to turn on.