An electric power tool provided with a plurality of operation modes, the tool comprising a motor that drives a tool output shaft to which a tool element is attached; a manipulation input receiving unit which receives a manipulation input for rotating the motor by a user; a mode changeover unit (37, 38) that has one manipulation portion which can be displaced by the user, and, by displacing the manipulation portion to one of a plurality of set positions which are individually set per operation mode, makes the electric power tool operate at one of the operation modes corresponding to the set position; a rotation drive force transmitting unit that transmits a rotation drive force of the motor to the tool output shaft, and includes a plurality of types of mechanical transmission mechanisms (55, 56, 57) which differ in mechanical transmission methods, the rotation drive force transmitting unit being configured to switch various mechanical links of the plurality of types of the mechanical transmission mechanisms (55, 56, 57) to one of the mechanical transmission mechanisms (55, 56, 57) corresponding to the set position of the manipulation portion in conjunction with the displacement manipulation of the manipulation portion, thereby to transmit the rotation drive force of the motor to the tool output shaft via the switched mechanical transmission mechanism (55, 56, 57); an electric signal output unit (37, 38) that outputs an electric signal corresponding to the set position of the manipulation portion; and a motor control unit that sets a control method of the motor to a control method preset for the electric signal, among a plurality of different types of control methods, based on the electric signal from the electric signal output unit (37, 38), and controls the motor by the set control method, based on manipulation particulars of the manipulation input receiving unit by the user, characterised in that the plurality of operation modes comprises at least two specified operation modes at each of which a predetermined control parameter corresponding to the operation mode is used to control the motor, and the control parameter can be changed to one of a plurality of different values by user operation, the at least two specified operation modes including an impact mode, in which the tool output shaft is rotated and intermittent hammering can be applied to the tool output shaft in its rotation direction and the control parameter is a maximum rotation frequency, and a clutch mode, in which the control parameter is a set torque value, and wherein the electric power tool further comprises: a memory that stores the control parameter; a setting change manipulation unit that is shared among the specified operation modes and that is manipulated by the user to change the control parameter corresponding to each of the at least two specified operation modes; and a parameter control unit that, when the operation mode of the electric power tool is set at one of the at least two specified operation modes, accepts change by the setting change manipulation unit to the control parameter corresponding to the specified operation mode that is set and stores the changed control parameter in the memory. a memory that stores the control parameter; a setting change manipulation unit that is shared among the specified operation modes and that is manipulated by the user to change the control parameter corresponding to each of the at least two specified operation modes; and a parameter control unit that, when the operation mode of the electric power tool is set at one of the at least two specified operation modes, accepts change by the setting change manipulation unit to the control parameter corresponding to the specified operation mode that is set and stores the changed control parameter in the memory.