A bipolar transistor is provided with an emitter layer, a base layer and a collector layer. The emitter layer is formed above a substrate and is an n-type conductive layer including a first nitride semiconductor. The base layer is formed on the emitter layer and is a p-type conductive including a second nitride semiconductor. The collector layer is formed on the base layer and includes a third nitride semiconductor. The collector layer, the base layer and the emitter layer are formed such that a crystal growth direction to the substrate surface is parallel to a substrate direction of [000-1]. The third nitride semiconductor contains InycAlxcGa1-xc-ycN (0•xc•1, 0•yc•1, 0