A method of reducing transmission power is provided. In the method, a signal is transmitted by performing maximum power reduction (MPR) on maximum output power for the signal to be transmitted, when multi-cluster transmission is performed in a single component carrier. Here, the MPR is performed differently depending on a resource allocation ratio A. The resource allocation ratio A is defined as a ratio between NRB—agg and NRB—alloc. The NRB—agg represents the number of resource blocks (RBs) in a channel band, and the NRB—alloc represents the total number of RBs transmitted at the same time.