PURPOSE:To smoothly discharge soil and to improve excavation efficiency, by a method wherein a bucket shell is openably mounted to a bucket body, a hydraulic cylinder is provided, and a blade is vertically movably attached to a piston rod. CONSTITUTION:A blade 18 is separated from upper plates 16a and 17a of bucket shells 16 and 17 with the aid of a hydraulic cylinder 20, and the bucket shells are held in an opening attitude. The bucket shells 16 and 17 are pushed in, soil is scooped in the shells 16 and 17, and the shells 16 and 17 are closed through contraction of the hydraulic cylinder 20. The bucket shells are lifted up to a ground, the blade 18 is lowered within the shells 16 and 17 through expansion of the cylinder 20 to discharge soil. This enables smooth discharge of soil by means of the blade irrespective of quality of soil excavated by the bucket shells.