Abstract: The invention relates to an operation mode switching device comprising: a rotatable driving unit; a manipulation signal and an operation for switching operation mode generated by a change in the manipulation signal; and a processing portion electrically connected to the driving unit and receiving the manipulation signal and the operation for switching operation mode, the processing portion is capable of receiving the manipulation signal to drive the driving unit, the processing portion receives the operation for switching operation mode within a time interval, the processing portion determines that it is an operation mode switching request, and the processing portion is capable of modulating an operation mode of the driving unit by performing the operation for switching operation mode through the manipulation signal of controlling an electric tool originally, and an operation mode switching function can be added without adding components and modifying an original design.