An objective of the present invention is to provide a counterweight of a power shovel interchangeable with that of a superordinate model without affecting a rear end radius of the shovel at the time of rotation. In the power shovel 50 in which the counterweight is formed at the rear part of a vehicle body frame 11 extended from a front end to a rear end of a lower part of a rotation upper body 10, and an engine 14 is mounted on the rear part of the vehicle body frame 11, an additional weight 12 is placed in a space between the rear part of the vehicle body frame 11 and the engine 14.