In a transmission device used in a wireless video transmission system in which a medical image is transmitted and received by radio communication, a transmission unit is capable of performing radio communication with a plurality of receiving devices connected to a plurality of display apparatuses. A control unit acquires an identifier for identifying a receiving device connected to a selected single display apparatus when an instruction is received to select one display apparatus on which the medical image is to be displayed from among the display apparatuses, and controls the transmission unit such that the identifier will be used when the medical image is transmitted.