In a spread spectrum communication system, one (W.sub.n) of a series of orthogonal codes for spectrum spreading is assigned to signal-to-noise ratio measurement in a terminal. On the basis of a noise signal detected by de-spreading a signal received from an antenna with the above described orthogonal code (W.sub.n) and a pilot signal, each terminal derives a signal-to-noise ratio. Each terminal transmits the signal-to-noise ratio to the base station as a power control signal. On the basis of signal-to-noise information received from each terminal as the power control signal, the base station controls signal transmission power for each terminal.