A transmitter for averagedly suppressing the variation in input level of an amplifier according to variation in carrier level. The transmitter includes an input power calculation section for calculating mean input power of each carrier, an output power calculating section for calculating mean output power of each carrier after the carrier band is limited, a monitoring section for identifying a carrier having the maximum mean input power, acquiring the maximum value, acquiring the mean output power of the identified carrier, determining the ratio of the mean input power to the mean output power, and calculating level control information which is the ratio of the ratio determined above to a predetermined expected value, and a signal level adjusting section for adjusting the level of a multicarrier signal by multiplying the level control information outputted from the monitoring section.