A base station apparatus in a wireless communication system that includes the base station apparatus and a terminal capable of connecting to the base station apparatus in a first system and connecting to another apparatus in a second system, the base station apparatus comprising: obtainment means for, when a failure has occurred in connection in the second system between the terminal and the another apparatus, obtaining, from the terminal, a report that includes a first part indicating a reason of failure occurrence and a second part indicating a candidate apparatus for a connection switchover destination in the second system; determination means for determining whether or not the reason of failure occurrence is suspension of communication functions of the terminal in the second system; and control means for performing a first connection control wherein in the first connection control, a connection of the terminal in the second system is stopped by transmitting an instruction to stop the connection to the terminal and the another apparatus, and by receiving, from the terminal, a report indicating that the connection is stopped in a case where it is determined that the reason of failure occurrence is suspension of communication functions of the terminal in the second system, and a second connection control based on the second part in the obtained report, wherein in the second connection control, a connection of the terminal with the another apparatus is switched to a connection with the candidate apparatus, by transmitting, to the terminal, the another apparatus, and the candidate apparatus, a notification for changing a connection destination of the terminal in the second system from the another apparatus to the candidate apparatus, and by receiving from the terminal a message indicating that a connection between the terminal and the candidate apparatus has been established in a case where it is determined that the reason of failure occurrence is not suspension of communication functions of the terminal in the second system. obtainment means for, when a failure has occurred in connection in the second system between the terminal and the another apparatus, obtaining, from the terminal, a report that includes a first part indicating a reason of failure occurrence and a second part indicating a candidate apparatus for a connection switchover destination in the second system; determination means for determining whether or not the reason of failure occurrence is suspension of communication functions of the terminal in the second system; and control means for performing a first connection control wherein in the first connection control, a connection of the terminal in the second system is stopped by transmitting an instruction to stop the connection to the terminal and the another apparatus, and by receiving, from the terminal, a report indicating that the connection is stopped in a case where it is determined that the reason of failure occurrence is suspension of communication functions of the terminal in the second system, and a second connection control based on the second part in the obtained report, wherein in the second connection control, a connection of the terminal with the another apparatus is switched to a connection with the candidate apparatus, by transmitting, to the terminal, the another apparatus, and the candidate apparatus, a notification for changing a connection destination of the terminal in the second system from the another apparatus to the candidate apparatus, and by receiving from the terminal a message indicating that a connection between the terminal and the candidate apparatus has been established in a case where it is determined that the reason of failure occurrence is not suspension of communication functions of the terminal in the second system. <EOS>