A power tool comprising: a motor configured to drive an end bit; a fan configured to be driven by the motor and defining an axis and a radial direction; and a housing accommodating the motor and the fan therein, the housing including: a peripheral wall having a ventilation hole formed therein, the ventilation hole being positioned adjacent to the fan and having a shape defined by a circumferential surface whose length in the radial direction is coincident with a thickness of the peripheral wall; and a grid configured to partly cover the ventilation hole and including at least one elongated portion (23A-23C) extending in an longitudinal direction perpendicular to the radial direction and along the circumferential direction of the housing, characterized in that: a distance from the axis of the fan to the circumferential surface is different from a distance from the axis of the fan to one elongated portion (23A-23C) in the radial direction of the fan, if a plurality of elongated portions (23A-23C) are provided, the one elongated portion (23A-23C) being an elongated portion closest to the circumferential surface among the plurality of elongated portions (23A-23C), or if a single elongated portion is provided, the one elongated portion being the single elongated portion. a motor configured to drive an end bit; a fan configured to be driven by the motor and defining an axis and a radial direction; and a housing accommodating the motor and the fan therein, the housing including: a peripheral wall having a ventilation hole formed therein, the ventilation hole being positioned adjacent to the fan and having a shape defined by a circumferential surface whose length in the radial direction is coincident with a thickness of the peripheral wall; and a grid configured to partly cover the ventilation hole and including at least one elongated portion (23A-23C) extending in an longitudinal direction perpendicular to the radial direction and along the circumferential direction of the housing, characterized in that: a distance from the axis of the fan to the circumferential surface is different from a distance from the axis of the fan to one elongated portion (23A-23C) in the radial direction of the fan, if a plurality of elongated portions (23A-23C) are provided, the one elongated portion (23A-23C) being an elongated portion closest to the circumferential surface among the plurality of elongated portions (23A-23C), or if a single elongated portion is provided, the one elongated portion being the single elongated portion. a peripheral wall having a ventilation hole formed therein, the ventilation hole being positioned adjacent to the fan and having a shape defined by a circumferential surface whose length in the radial direction is coincident with a thickness of the peripheral wall; and a grid configured to partly cover the ventilation hole and including at least one elongated portion (23A-23C) extending in an longitudinal direction perpendicular to the radial direction and along the circumferential direction of the housing, characterized in that: a distance from the axis of the fan to the circumferential surface is different from a distance from the axis of the fan to one elongated portion (23A-23C) in the radial direction of the fan, if a plurality of elongated portions (23A-23C) are provided, the one elongated portion (23A-23C) being an elongated portion closest to the circumferential surface among the plurality of elongated portions (23A-23C), or if a single elongated portion is provided, the one elongated portion being the single elongated portion.