An identification apparatus includes a guide member defining a guide path, a scanning portion that scans the sheet inserted in the guide path, a first detection portion disposed upstream of the scanning portion in an insertion direction of the sheet in the guide path that detects presence/absence of the sheet, and a second detection portion disposed downstream of the scanning portion in the insertion direction in the guide path and detects presence/absence of the sheet. The identification apparatus is configured to start measurement of a surface property of the sheet by the scanning portion in response to a change in a detection result of one of the first detection portion or the second detection portion, and complete the measurement in response to a change in a detection result whichever of the first detection portion or the second detection portion not used in determining the start of the measurement.