PURPOSE: To improve a frontal vision field and maintain operability by constituting an operation device integrally with an operation seat which is ascendable/ descendable.

CONSTITUTION: The operation seat of a work vehicle is constituted by constituting integrally with a seat 1 a travel operation device 3 to regulate the drive condition of a travel device 2, a work operation device or the like to regulate the drive condition of a work device 4 and at the same time providing standingly in shaft attachment a support arm 7 rotatably up and down at the front side lower part position of the seat 1 at a vehicle body 6 and supporting the seat 1 by means of the support arm 7.