A controlling method and a radio base station apparatus capable of variably determining a Transmission Time Interval (TTI) length in accordance with a communication environment of a mobile terminal is disclosed. The radio base station apparatus includes a receiving section receiving information via an uplink channel; and a scheduler variably determining a Transmission Time Interval (TTI) length for any one of an uplink shared channel and a downlink shared channel or both based on at least any of a moving speed of a mobile terminal, location of the mobile terminal in a cell, a provided throughput value, and a number of retransmissions obtained from the received information. Preferably, the scheduler includes a TTI length allocation table describing relationships between parameter values and the corresponding TTI length, the parameters being used for estimating the location and/or the moving speed of the mobile terminal.