To provide a recording device which can detect a correct sheet thickness and can appropriately adjust a platen gap in a wide temperature range, and to provide a platen gap adjustment mechanism and a platen gap adjustment method.

The recording device includes the platen gap adjustment mechanism 30 for adjusting the platen gap between a recording head 20 and a platen 25. The platen gap adjustment mechanism 30 measures a distance between the recording head 20 and the platen 25, and also measures a distance between the recording head 20, and a sheet arranged between the recording head 20 and the platen 25. The sheet thickness is calculated from a difference of the measured values, and is corrected according to temperatures. The platen gap is adjusted on the basis of the sheet thickness after corrected. Furthermore, the platen gap adjustment mechanism 30 detects the temperature on the basis of the distance measured value between the recording head 20 and the platen 25.