A mobile station (100 1 to 100 3) for communicating with a base station, the mobile station comprising: an uplink signal transmitting unit configured to transmit an uplink signal at a transmit timing of the uplink signal, in accordance with a SC-FDMA scheme or an OFDMA scheme; an uplink signal receiving unit configured to receive from the base station an adjustment amount indicator for adjusting the transmit timing of the uplink signal; and an uplink transmit timing adjustment unit configured to adjust the transmit timing of the uplink signal based on the received adjustment amount indicator, wherein: when the mobile station (110 1 to 110 3) is in a communication initiation state, the uplink signal receiving unit is configured to receive an adjustment amount indicator whose values span a first adjustment amount range adapted for the communication initiation state, the value of the received adjustment amount indicator being defined by a plurality of m bits; and when the mobile station (100 1 to 100 3) is in an ongoing communication state between the mobile station and the base station, the uplink signal receiving unit is configured to receive an adjustment amount indicator whose values span a second adjustment amount range adapted for the ongoing communication state between the mobile station and the base station, the value of the received adjustment amount indicator being defined by a plurality of n bits, where m > n such that the first adjustment amount range is greater than the second adjustment amount range. an uplink signal transmitting unit configured to transmit an uplink signal at a transmit timing of the uplink signal, in accordance with a SC-FDMA scheme or an OFDMA scheme; an uplink signal receiving unit configured to receive from the base station an adjustment amount indicator for adjusting the transmit timing of the uplink signal; and an uplink transmit timing adjustment unit configured to adjust the transmit timing of the uplink signal based on the received adjustment amount indicator, wherein: when the mobile station (110 1 to 110 3) is in a communication initiation state, the uplink signal receiving unit is configured to receive an adjustment amount indicator whose values span a first adjustment amount range adapted for the communication initiation state, the value of the received adjustment amount indicator being defined by a plurality of m bits; and when the mobile station (100 1 to 100 3) is in an ongoing communication state between the mobile station and the base station, the uplink signal receiving unit is configured to receive an adjustment amount indicator whose values span a second adjustment amount range adapted for the ongoing communication state between the mobile station and the base station, the value of the received adjustment amount indicator being defined by a plurality of n bits, where m > n such that the first adjustment amount range is greater than the second adjustment amount range. when the mobile station (110 1 to 110 3) is in a communication initiation state, the uplink signal receiving unit is configured to receive an adjustment amount indicator whose values span a first adjustment amount range adapted for the communication initiation state, the value of the received adjustment amount indicator being defined by a plurality of m bits; and when the mobile station (100 1 to 100 3) is in an ongoing communication state between the mobile station and the base station, the uplink signal receiving unit is configured to receive an adjustment amount indicator whose values span a second adjustment amount range adapted for the ongoing communication state between the mobile station and the base station, the value of the received adjustment amount indicator being defined by a plurality of n bits, where m > n such that the first adjustment amount range is greater than the second adjustment amount range.