A battery pack for a power tool, comprising: a battery pack body capable of being removed from the power tool in a removing direction, wherein the battery pack body includes left and right side portions (10L, 10R) disposed on opposite sides, a bottom side portion extending substantially perpendicular to the left and right side portions (10L, 10R), a front side portion extending substantially perpendicular to the left, right and bottom side portions (10L, 10R, 10B), and left and right corner portions defined between the front side portion and the left and right side portions (10L, 10R), respectively; a lock device capable of releasably locking the battery pack body against the power tool; and an operation member operable for unlocking the lock device and movably supported within the front side portion; characterized in that the battery pack body includes a left finger engaging portion engageable with a finger or fingers of an operator in the removing direction of the battery pack body and disposed at the left side portion and a right finger engaging portion engageable with a finger or fingers of an operator in the removing direction of the battery pack body and disposed at the right side portion; wherein the left finger engaging portion extends along the left corner portion; the right finger portion extends along the right corner portion; and the left finger engaging portion and the right finger engaging portion are positioned relative to the operation member such that the operation member can be operated by one of the fingers of one hand of an operator while the left and right finger engaging portions (14, 15) being engaged by the other two of the fingers of the same hand of the operator. a battery pack body capable of being removed from the power tool in a removing direction, wherein the battery pack body includes left and right side portions (10L, 10R) disposed on opposite sides, a bottom side portion extending substantially perpendicular to the left and right side portions (10L, 10R), a front side portion extending substantially perpendicular to the left, right and bottom side portions (10L, 10R, 10B), and left and right corner portions defined between the front side portion and the left and right side portions (10L, 10R), respectively; a lock device capable of releasably locking the battery pack body against the power tool; and an operation member operable for unlocking the lock device and movably supported within the front side portion; characterized in that the battery pack body includes a left finger engaging portion engageable with a finger or fingers of an operator in the removing direction of the battery pack body and disposed at the left side portion and a right finger engaging portion engageable with a finger or fingers of an operator in the removing direction of the battery pack body and disposed at the right side portion; wherein the left finger engaging portion extends along the left corner portion; the right finger portion extends along the right corner portion; and the left finger engaging portion and the right finger engaging portion are positioned relative to the operation member such that the operation member can be operated by one of the fingers of one hand of an operator while the left and right finger engaging portions (14, 15) being engaged by the other two of the fingers of the same hand of the operator.