A mobile terminal device for performing multi-carrier communication with a base station device can improve communication quality while reducing the data amount without lowering accuracy of feedback information. In the mobile station device (100), a reception level measuring unit (135) measuring SINR as a reception level for each chunk formed by a plurality of sub-carriers according to a known signal; a control information transmission control unit (160) transmits feedback information (CQI information) based on the communication quality of each chunk to a base station device (200); a relative value calculation unit (150) calculates a relative value of MCS corresponding to the reception level between adjacent chunks from the reception level of each chunk; and a CQI information generation unit (155) generates feedback information (CQI information) from an absolute value of MCS corresponding to the reception level of the reference chunk and a relative value of MCS corresponding to the reception level between the adjacent chunks.