In a radio communication system which uses pilot signals during transmission from a user terminal to a base station, the base station creates and stores a rank table on a peak to average power ratio of each pilot pattern, extracts a transmission power of the user terminal or a power difference between a maximum transmission power and the transmission power of the user terminal on the basis of a receive signal from the user terminal, and allocates a pilot pattern of which peak to average power ratio is good to a user terminal of which transmission power is great, or the power difference is small, with reference to the rank table. Or a pilot pattern in a rank according to the transmission status (e.g. transmission power, distance from the base station) of the user terminal is adaptively allocated to the user terminal.