A terminal device configured to perform D2D transmission by a higher layer includes: a reception unit receiving from a base station device one or a plurality of first parameters relating to transmit power and receiving a second parameter for configuring a first transmission resource from the base station device; and a transmission unit performing, upon receipt of the second parameter in an RRC idle state, the D2D transmission using the first transmission resource with the transmit power in accordance with a first parameter corresponding to an authorized range among the one or plurality of first parameters.