A secret key generation apparatus and method are provided. The secret key generation apparatus includes at least one antenna, amplification/phase controllers, a transceiver, and a random signal controller. The antenna receives a wireless signal from a counterpart terminal that performs wireless communication. The amplification/phase controllers control the amplification gain and phase of the wireless signal that is received via at least one antenna. The transceiver measures the status of a wireless channel using the wireless signal having the controlled amplification gain and phase, determines parameters based on results of the measurement, and generates a secret key based on results of the determination. The random signal controller controls the amplification/phase controllers so that the amplification gain and phase are adjusted whenever the transceiver generates a secret key.