A base station device configured to perform wireless communication with a mobile station device, the base station device comprising: a random access identification information storage storing random access identification information and mobile station device identification information, C-RNTI, correlated with the random access identification information, the random access identification information being allocated by the base station device to the mobile station device, and the mobile station device identification information, C-RNTI, identifying the mobile station device; a random access receiver configured to receive random access identification information transmitted by the mobile station device having performed random access; a scheduler configured to determine whether to transmit random access response information that is a response to the random access corresponding to the random access identification information received by using the mobile station device identification information, C-RNTI, or by using identification information, RA-RNTI, not being used for mobile station device identification information, the identification information, RA-RNTI, being allocated for transmitting the response to the random access, in a case that the random access identification information received is stored in the random access identification information storage while being correlated with the mobile station device identification information, C-RNTI; and a transmitter configured to allocate and transmit the random access response information based on the determination by the scheduler, wherein the scheduler is configured to determine, based on an amount of downlink traffic, whether to transmit the random access response information by using the mobile station device identification information, C-RNTI, or by using the identification information, RA-RNTI, in the case that the random access identification information received is stored in the random access identification information storage while being correlated with the mobile station device identification information, C-RNTI. a random access identification information storage storing random access identification information and mobile station device identification information, C-RNTI, correlated with the random access identification information, the random access identification information being allocated by the base station device to the mobile station device, and the mobile station device identification information, C-RNTI, identifying the mobile station device; a random access receiver configured to receive random access identification information transmitted by the mobile station device having performed random access; a scheduler configured to determine whether to transmit random access response information that is a response to the random access corresponding to the random access identification information received by using the mobile station device identification information, C-RNTI, or by using identification information, RA-RNTI, not being used for mobile station device identification information, the identification information, RA-RNTI, being allocated for transmitting the response to the random access, in a case that the random access identification information received is stored in the random access identification information storage while being correlated with the mobile station device identification information, C-RNTI; and a transmitter configured to allocate and transmit the random access response information based on the determination by the scheduler, wherein the scheduler is configured to determine, based on an amount of downlink traffic, whether to transmit the random access response information by using the mobile station device identification information, C-RNTI, or by using the identification information, RA-RNTI, in the case that the random access identification information received is stored in the random access identification information storage while being correlated with the mobile station device identification information, C-RNTI.