The present invention can perform communication efficiently. In a case that (1) the terminal apparatus is configured to monitor a first PDCCH candidate in a CSS and a second PDCCH candidate in a USS according to a DCI format with a C-RNTI, (2) a set of resource elements constituting the first PDCCH candidate is the same as a set of resource elements constituting the second PDCCH candidate, (3) a higher layer parameter is not set, and/or (4) the size of the DCI format corresponding to the first PDCCH candidate is the same as the size of the DCI format corresponding to the second PDCCH candidate, a terminal apparatus regards that a PDCCH with the DCI format is transmitted or received in the first PDCCH candidate when the PDCCH with the DCI format is received in the second PDCCH candidate.