The invention relates to a power device which can provide power for tool main bodies of electric tools. Each tool main body comprises a tool shell and a working part supported by the tool shell. The power device comprises a main shell, a motor supported by the main shell and an energy providing unit. The energy providing unit provides energy for the motor. The main shell can be detachably installed on the tool shells. When the main shell is installed on the tool shells, the working parts can be driven by the motor. The power device can be commonly used for different tool main bodies, therefore, the universality of the power device is improved, and the using cost is lowered for users.