A percussion driver drill comprising: a housing; a motor provided in the housing; a gear case (9, 10) provided in the housing, the gear case (9, 10) having a tubular portion protruding frontward; a planetary gear speed reduction mechanism provided in the gear case (9, 10); a spindle rotatably supported in the tubular portion of the gear case (9, 10), the spindle being configured to protrude from the housing and to receive an output of the motor transmitted through the planetary gear speed reduction mechanism; a clutch mechanism including a final-stage internal gear rotatably provided at a final stage of the planetary gear speed reduction mechanism, a plurality of engageable members held in the gear case (9, 10) and configured to be engageable with an end face of the internal gear, and a coil spring disposed frontwardly of the plurality of engageable members and configured to press the plurality of engageable members against the end face of the internal gear, the clutch mechanism being configured to cause the internal gear to run idle, thereby interrupting transmission of torque, at overload beyond a pressing force of the coil spring; a cam mechanism provided inside the tubular portion and configured to selectively impart an axial vibratory motion to the spindle; and a vibration mechanism including a switch member provided outside the tubular portion and configured to be rotatable to a first angular position in which the switch member is interlocked with the cam mechanism to render the cam mechanism operable and a second angular position in which the switch member is released from the cam mechanism to render the cam mechanism inoperable, a coupling member connected with the switch member, and an operating member provided outside the switch member in a radial direction of the tubular portion, connected with the coupling member to establish connection with the switch member, and configured to be operable to rotate the switch member into one of the first and second angular positions, whereby a rotatory motion of the switch member to the first angular position imparted through the operating member makes the cam mechanism capable of imparting the axial vibratory motion to the spindle, characterized in that the coil spring of the clutch mechanism is disposed between the switch member and the operating member of the vibration mechanism, and the coupling member is disposed to pass through a gap between the plurality of engageable members and detour around a rear end of the coil spring. a housing; a motor provided in the housing; a gear case (9, 10) provided in the housing, the gear case (9, 10) having a tubular portion protruding frontward; a planetary gear speed reduction mechanism provided in the gear case (9, 10); a spindle rotatably supported in the tubular portion of the gear case (9, 10), the spindle being configured to protrude from the housing and to receive an output of the motor transmitted through the planetary gear speed reduction mechanism; a clutch mechanism including a final-stage internal gear rotatably provided at a final stage of the planetary gear speed reduction mechanism, a plurality of engageable members held in the gear case (9, 10) and configured to be engageable with an end face of the internal gear, and a coil spring disposed frontwardly of the plurality of engageable members and configured to press the plurality of engageable members against the end face of the internal gear, the clutch mechanism being configured to cause the internal gear to run idle, thereby interrupting transmission of torque, at overload beyond a pressing force of the coil spring; a cam mechanism provided inside the tubular portion and configured to selectively impart an axial vibratory motion to the spindle; and a vibration mechanism including a switch member provided outside the tubular portion and configured to be rotatable to a first angular position in which the switch member is interlocked with the cam mechanism to render the cam mechanism operable and a second angular position in which the switch member is released from the cam mechanism to render the cam mechanism inoperable, a coupling member connected with the switch member, and an operating member provided outside the switch member in a radial direction of the tubular portion, connected with the coupling member to establish connection with the switch member, and configured to be operable to rotate the switch member into one of the first and second angular positions, whereby a rotatory motion of the switch member to the first angular position imparted through the operating member makes the cam mechanism capable of imparting the axial vibratory motion to the spindle, characterized in that the coil spring of the clutch mechanism is disposed between the switch member and the operating member of the vibration mechanism, and the coupling member is disposed to pass through a gap between the plurality of engageable members and detour around a rear end of the coil spring.