Pulse torque generator and power tool having the same

A pulse torque generator utilizing a magnetic coupling, and an electric power tool provided with the pulse torque generator. The pulse torque generator includes an input shaft extending in its axial direction and having a hollow section providing a hollow space, and an output shaft rotatably provided in the hollow space. A magnetic fluid is encapsulated in a hollow space between the input shaft and output shaft. A magnetic field generating unit is disposed, and magnetic segments are provided in the input shaft. A magnetic fluid provides a magnetic fluid bridge bridging between the input shaft and the output shaft each time the magnetic segment is brought into confrontation with the magnetic field generating unit.