PURPOSE: To facilitate assembling and tuning operations by installing a handle frame provided with a frame cover covering an upper opening part rotatably in an upper end of a transmission case, while trimming a sliding operator and an engager in an inner part of the handle frame.

CONSTITUTION: When a main shift lever 19 is rotated up and down, a shift transmission mechanism in a transmission case is operated for shifting via a shift yoke 18 and a sliding shaft 1. Likewise, when a shift yoke 21 for sub- shifting is operated for rotation, a sub-shifting mechanism is operated for shifting via an inside sliding shaft 13. In addition, when an operating lever 15 is operated and engagement of a turning claw 17 is released, an operating lever and a handle frame 4 are rotated around the sliding shaft 1. At this time, as mentioned above, an operator 5 sliding the sliding shaft 1 and an engager 6 engaging the handle frame 4 at a rotating position are trimmed in the handle frame 4 respectively. Then, an upper opening part of the handle frame 4 is covered with an unillustrated frame cover.