Disclosed is a base station apparatus which allows an idle mode UE, in a small cell using S-NCT, to recognize the small cell and to receive a DCI. The base station apparatus is configured to use a carrier configuration which has no region for mapping a PDCCH and in which an EPDCCH is mapped in a data region. The base station apparatus includes: master information generating section 101 configured to generate allocation information indicating a resource which forms a search space in the EPDCCH and being scrambled with a cell ID of the base station apparatus; and transmitting section 107 configured to transmit the allocation information, a detection signal indicating the cell ID, and a control signal assigned in the search space.