PURPOSE: To prevent the generation of vibrating sound caused by the mincing vibration of a bonnet side plate part and allow a bonnet to be opened desirably without interfering with a member positioned behind by closably supporting the rear lower part of the side plate of the bonnet opened with the front part pulled up.

CONSTITUTION: A longitudinal pair of parallel links 14, 15 are provided in the backward inclined state at the side of the rear lower part of a bonnet side plate part 6b. The upper end side of the respective parallel links 14, 15 are pivotally supported on the body side so as to be rotatable around a lateral shaft, while the lower side of the respective parallel links 14, 15 are pivotally connected to the bonnet side plate part 6b through connecting pins 22, 23, and a front side pin through-hole 20 is formed into oblong shape. A bonnet 6 is thereby ascends parallelly by the upward rotation of the front and rear parallel links 14, 15, and the front side connecting pin 22 moves around the rear side connecting pin 23 so as to pull up the front part of the bonnet 6.