To provide a transmission gear shifting device requiring only a narrow space as a range of installation.

This transmission gear shifting device, which has a lever control 62 protrusion 84 abutting on one of a plurality of moderation grooves 54 respectively different radius from the rotation center to the bottom of a cam 48, has the cam 48 rotate when a shaft 24 is operated to rotate around itself and the lever control 62 protrusion 84 move along the outer circumference 52 of the cam 48 to another moderation groove 54 with a knob 26 button 32 pushed in and a rod 36 connected to the cam 48. Thus the lever control 62 rotates and causes an automatic transmission 13 to operate through a wire 68 and change the shift rage. Consequently, the transmission gear shifting device 10 can be installed only if there is enough space for the shat 24 to stick out because the shaft 24 is only to be rotated around its own axis.