The present invention is capable of suppressing gear shift shocks or delays in acceleration with no interruption of driving force and reducing the weight. Disclosed is a transmission which is provided, with multiple stage shift gears so arranged to shift a number of dog clutches to shift a gear to the upper stage of the multiple stage shift gears, and is characterized in that a guide part is provided to a shift operation section and the dog clutches on each of the sages so as to move the lower dog clutch in a neutral direction by a coasting torque acting on the lower stage by a shift rotation of the upper stage to release a meshing engagement when meshing engagements of the lower and upper dog clutches are simultaneously performed by an operation of the shift operation section.