A bias circuit providing different bias voltages depending on a power mode through a simple circuit, and a power amplifier having the same are provided. The bias circuit and the power amplifier include a bias setting unit configured to vary a voltage level of a control signal controlling a bias voltage according to an operation of a first transistor being switched-off in a high power mode and switched-on in a low power mode. A bias supplying unit includes a bias supplying transistor switched based on the control signal, to supply the bias voltage having a voltage level according to a switching operation of the bias supplying transistor.