though the wet multiplate friction clutch 5 is disengaged the input shaft 3 stops revolving and in gear parking is enabled in the same way as the above embodiment accordingly in the present embodiment in the same way as the above embodiment compared to using a conventional multiplate disc type countershaft brake the present invention has a simple construction and is able to exert a reliable gear brake function further the seal of the dividing wall 35 can be maintained and a smaller amount of force can be used to restrict the rotation thereby enabling more reliable in gear parking in addition for its lubrication since the gear parking brake 31 according to the present invention is formed in the moist chamber containing the wet multiplate friction clutch 5 the atf oil used for the wet multiplate friction clutch 5 and the fluid coupling 4 can be used in that state for lubrication and this can prevent reduction of the brake power created by lubricative defects in summary the present invention can produce the superior effects described below 1 a brake drum is formed on the input shaft of the transmission and this brake drum is automatically tightened by a brake band when the engine stops thereby enabling in gear parking when the transmission has been put into gear even though the engine has stopped and the friction clutch is disengaged because the rotation of the input shaft is restricted 2 further in comparison.