Provided is a transport device including a first transport section that is driven at a first transport speed and transports a recording medium interposed therein, a second transport section that is driven at a speed different from the first transport speed, is located at a downstream of the first transport section in a transport direction, and transports the recording medium interposed therein, a detection section that detects variations in a driving load of the second transport section before and after the recording medium is discharged from the first transport section, and a derivation section that derives a thickness of the recording medium based on the variations.