Disclosed is a power control method for a mobile station which has at least one compressed mode frame. A compressed mode frame includes a data transmission duration where data is transmitted at a first frequency, and a data transmission-off duration where a second frequency is searched to perform an inter-frequency handoff to the second frequency. The transmission power during the data transmission duration is increased to compensate for the loss of transmission power during the data transmission-off duration. In the method, a base station sets a power control threshold depending on the length of the data transmission-off duration. The base station receives transmission power-increased data and compares the received power of the data signal with the power control threshold. The base station generates a power-up command when the power control threshold is higher than the receiving power, and generates a power-down command when the power control threshold is lower than the receiving power.