PURPOSE: To discharge even viscous soil easily, and to improve the efficiency of execution by pushing a cylindrical bucket body for a bucket excavator into the ground surface of viscous soil and excavating viscous soil, pushing out an earth-removing plate and discharging viscous soil.

CONSTITUTION: In an excavating mechanism 28, an opening is directed toward the ground surface of viscous soil, a bucket body 32 is pushed into the ground surface, viscous soil is taken into the bucket body 32, a discharge mechanism 43 pulls up the bucket body 32, and an earth-removing plate 33 is pushed out, thus discharging viscous soil. In the discharge mechanism 43 with a cylinder 34, a pressure accumulator 38 and a check valve 40, the cylinder 34 is shrunk when the bucket body 32 is pushed into the ground surface, a fluid is stored in the pressure accumnulator 38 through the check valve 40, the fluid is flowed into a head-side working chamber through an on-off valve 41, and the earth- removing plate 33 is pushed out by the cylinder 34, thus discharging viscous soil. In a bucket excavator with a rotating pushing mechanism 1 and a grip mechanism 15, the rotating pushing mechanism 1 turns a casing tube 10 and pushs the casing tube 10 into the ground, and pushs in the bucket body 32.