The present invention discloses an insulated gate bipolar transistor (IGBT) and a manufacturing method thereof. The IGBT includes: a gallium nitride (GaN) substrate, a first GaN layer with a first conductive type, a second GaN layer with a first conductive type, a third GaN layer with a second conductive type or an intrinsic conductive type, and a gate formed on the GaN substrate. The first GaN layer is formed on the GaN substrate and has a side wall vertical to the GaN substrate. The second GaN layer is formed on the GaN substrate and is separated from the first GaN layer by the gate. The third GaN layer is formed on the first GaN layer and is separated from the GaN substrate by the first GaN layer. The gate has a side plate adjacent to the side wall in a lateral direction to control a channel.