To provide a control device of a transmission which can reduce speed change time without addition and upsizing of components or deterioration of fuel economy.

An ECU pulls a sleeve out of a speed change gear pair at a current speed change stage when up-shift is required (Step S11), and starts the shift to a required speed change stage and a speed change stage higher than required (Step S15) and starts the press of a synchromesh mechanism with respect to a speed change gear pair at the required speed change stage and the speed change stage higher than required (Step S16) when the pull-out is determined to be completed (YES in Step S14), and releases the press of the synchromesh mechanism with respect to the speed change gear pair at the speed change stage higher than required (Step S18) when relative rotation speed of the mesh mechanism and speed change gear pair for forming required speed change stage is determined to be small than N0 (YES in Step S17).