An electric-power-driven working device comprising; a body case; a work tool projecting frontward out of a front portion of the body case; a motor driving the work tool; a battery for supplying electric power to the motor, wherein the battery is mounted on a battery mount-and-release portion and extends in an upper-lower direction and across a middle portion in a height direction of a rear portion of the body case; and a top handle extending in a front-rear direction, wherein the top handle is formed on an upper portion of the body case and includes a rear end portion arranged to an upper portion of the battery mount-and-release portion; the front portion of the body case housing the motor while the battery mount-and-release portion, on which the battery is mounted and from which the battery is released, is formed at the rear portion of the body case; characterized by a side handle arranged to a side face of the body case, extending from the front portion of the body case to the rear portion of the body case and including a rear end portion disposed rearward of and below an output shaft of the motor; the battery mount-and-release portion inclining in a way that a lower portion of the battery mount-and-release portion is disposed frontward of the upper portion of the battery mount-and-release portion and including a retaining portion to retain the battery and a battery case which receives a lower portion of the battery; and the battery case including right and left side walls (14a, 14a) and a rear end wall, the right and left side walls (14a, 14a) extending rearward from a lower portion of the retaining portion, the rear end wall extending from both the right and left side walls (14a, 14a), a space surrounded by the retaining portion, the right and left side walls (14a, 14a) and the rear end wall forming a space in which the lower portion of the battery is disposable, at an upper end of the battery case being formed an insertion opening through which the battery is insertable from upward, and at a lower end of the battery case being formed an opening portion having an opening bored through in the upper-lower direction. a body case; a work tool projecting frontward out of a front portion of the body case; a motor driving the work tool; a battery for supplying electric power to the motor, wherein the battery is mounted on a battery mount-and-release portion and extends in an upper-lower direction and across a middle portion in a height direction of a rear portion of the body case; and a top handle extending in a front-rear direction, wherein the top handle is formed on an upper portion of the body case and includes a rear end portion arranged to an upper portion of the battery mount-and-release portion; the front portion of the body case housing the motor while the battery mount-and-release portion, on which the battery is mounted and from which the battery is released, is formed at the rear portion of the body case; characterized by a side handle arranged to a side face of the body case, extending from the front portion of the body case to the rear portion of the body case and including a rear end portion disposed rearward of and below an output shaft of the motor; the battery mount-and-release portion inclining in a way that a lower portion of the battery mount-and-release portion is disposed frontward of the upper portion of the battery mount-and-release portion and including a retaining portion to retain the battery and a battery case which receives a lower portion of the battery; and the battery case including right and left side walls (14a, 14a) and a rear end wall, the right and left side walls (14a, 14a) extending rearward from a lower portion of the retaining portion, the rear end wall extending from both the right and left side walls (14a, 14a), a space surrounded by the retaining portion, the right and left side walls (14a, 14a) and the rear end wall forming a space in which the lower portion of the battery is disposable, at an upper end of the battery case being formed an insertion opening through which the battery is insertable from upward, and at a lower end of the battery case being formed an opening portion having an opening bored through in the upper-lower direction.