A wideband transimpedance amplifier circuit is provided. The wideband transimpedance amplifier circuit includes a common-gate transistor, a bias current controlling circuit and an amplifier circuit. The bias current controlling circuit is coupled to a source of the common-gate transistor. The amplifier circuit is coupled to a drain of the common-gate transistor. The bias current controlling circuit adjusts the input impedance of the wideband transimpedance amplifier circuit according to the output signal of the amplifier circuit.