The present invention proposes a transmission control device capable of shortening a switching time between forward control and reverse control of a transmission. The present invention relates to a transmission control device that controls a transmission, including: a forward power transmission mechanism configured to move a vehicle forward; and a reverse power transmission mechanism configured to reverse the vehicle. Each of the forward power transmission mechanism and the reverse power transmission mechanism includes a driving-side connector and a driven-side connector. The forward power transmission mechanism and the reverse power transmission mechanism are configured to be capable of changing a contact state where the driving-side connector and the driven-side connector are pushed to contact each other, a retracted state where pushing forces are released to retract the driving-side connector and the driven-side connector, and an intermediate state formed as the intermediate state between the contact state and the retracted state. When the vehicle is controlled based on a previously-generated control content including switching between forward control and reverse control, one of the forward control and the reverse control is performed by controlling one power transmission mechanism between the forward power transmission mechanism and the reverse power transmission mechanism to the contact state while controlling the other power transmission mechanism to the intermediate state.