A motor-driven screwdriver operation information indicator retrofittable to a screwdriver housing of a motor-driven screwdriver to indicate information related to an operation of the motor-driven screwdriver, the motor-driven screwdriver operation information indicator comprising: a supporting and securing member in the shape of a ring having an inner peripheral surface to be fitted around and on an outer peripheral surface of a rear end portion of the screwdriver housing of the motor-driven screwdriver, the supporting and securing member being configured to be secured to the rear end portion, with the inner peripheral surface fitted on the outer peripheral surface of the rear end portion; and an indicator housing that is a separate member from the supporting and securing member, the indicator housing having a securing part configured to be secured to a supporting and securing part formed on the outer peripheral surface of the supporting and securing member by being axially aligned with and advanced from a rear side of the supporting and securing part to be fitted to the supporting and securing part, the indicator housing being held at a rear position of the rear end portion of the screwdriver housing by securing the securing part to the supporting and securing part; the indicator housing comprising: an indication control circuit disposed in the indicator housing, the indication control circuit being connected to at least one circuit selected from between a motor-driven screwdriver drive control circuit disposed in the screwdriver housing and an external control circuit outside the screwdriver housing to transmit a signal related to an operation of the motor-driven screwdriver on a basis of a signal received from the at least one circuit; and an operation information indicating part disposed in the indicator housing to receive the signal related to the operation of the motor-driven screwdriver, which is transmitted from the indication control circuit, and to indicate information related to the operation of the motor-driven screwdriver. a supporting and securing member in the shape of a ring having an inner peripheral surface to be fitted around and on an outer peripheral surface of a rear end portion of the screwdriver housing of the motor-driven screwdriver, the supporting and securing member being configured to be secured to the rear end portion, with the inner peripheral surface fitted on the outer peripheral surface of the rear end portion; and an indicator housing that is a separate member from the supporting and securing member, the indicator housing having a securing part configured to be secured to a supporting and securing part formed on the outer peripheral surface of the supporting and securing member by being axially aligned with and advanced from a rear side of the supporting and securing part to be fitted to the supporting and securing part, the indicator housing being held at a rear position of the rear end portion of the screwdriver housing by securing the securing part to the supporting and securing part; the indicator housing comprising: an indication control circuit disposed in the indicator housing, the indication control circuit being connected to at least one circuit selected from between a motor-driven screwdriver drive control circuit disposed in the screwdriver housing and an external control circuit outside the screwdriver housing to transmit a signal related to an operation of the motor-driven screwdriver on a basis of a signal received from the at least one circuit; and an operation information indicating part disposed in the indicator housing to receive the signal related to the operation of the motor-driven screwdriver, which is transmitted from the indication control circuit, and to indicate information related to the operation of the motor-driven screwdriver. an indication control circuit disposed in the indicator housing, the indication control circuit being connected to at least one circuit selected from between a motor-driven screwdriver drive control circuit disposed in the screwdriver housing and an external control circuit outside the screwdriver housing to transmit a signal related to an operation of the motor-driven screwdriver on a basis of a signal received from the at least one circuit; and an operation information indicating part disposed in the indicator housing to receive the signal related to the operation of the motor-driven screwdriver, which is transmitted from the indication control circuit, and to indicate information related to the operation of the motor-driven screwdriver.