A drive device, comprising: a power converter that converts DC power, supplied by a DC power supply, into AC power to be provided to an electric motor; and a control unit that executes transmission/reception of data to/from an external device and activation control of the power converter in accordance with a control program, wherein the control program includes a first program for causing the control unit to function as a core unit and a second program for causing the control unit to function as a customization unit, wherein an access restriction is imposed on a storage area in which the first program is written, wherein the second program is for causing the control unit to function as a customization unit that receives from the external device a command value that designates a first operating state of the electric motor in terms of a first physical quantity, converts the command value into a first normalized command value by using an interconversion API read from a power converter control library and provided by a software module included in the first program, and provides the resultant first normalized command value to the core unit, and wherein the first program is for causing the control unit to function as a core unit that receives the first normalized command value that designates an operating state of the electric motor, converts the first normalized command value into a first physical quantity by using the interconversion API, and executes activation control of the electric motor in accordance with the physical quantity obtained from the received first normalized command value; and wherein the core unit executes a process for providing current values of physical quantities representing operating states of the electric motor to the customization unit, the process being a process for normalizing a value of a second physical quantity among said current values of physical quantities representing operating states of the electric motor by using the interconversion API and providing the second normalized physical quantity to the customization unit, wherein the interconversion API uses a predetermined reference value to normalize the value of the second physical quantity, and the customization unit then converts the second normalized physical quantity back into the second physical quantity by using the interconversion API and then sends the second physical quantity to the external device. a power converter that converts DC power, supplied by a DC power supply, into AC power to be provided to an electric motor; and a control unit that executes transmission/reception of data to/from an external device and activation control of the power converter in accordance with a control program, wherein the control program includes a first program for causing the control unit to function as a core unit and a second program for causing the control unit to function as a customization unit, wherein an access restriction is imposed on a storage area in which the first program is written, wherein the second program is for causing the control unit to function as a customization unit that receives from the external device a command value that designates a first operating state of the electric motor in terms of a first physical quantity, converts the command value into a first normalized command value by using an interconversion API read from a power converter control library and provided by a software module included in the first program, and provides the resultant first normalized command value to the core unit, and wherein the first program is for causing the control unit to function as a core unit that receives the first normalized command value that designates an operating state of the electric motor, converts the first normalized command value into a first physical quantity by using the interconversion API, and executes activation control of the electric motor in accordance with the physical quantity obtained from the received first normalized command value; and wherein the core unit executes a process for providing current values of physical quantities representing operating states of the electric motor to the customization unit, the process being a process for normalizing a value of a second physical quantity among said current values of physical quantities representing operating states of the electric motor by using the interconversion API and providing the second normalized physical quantity to the customization unit, wherein the interconversion API uses a predetermined reference value to normalize the value of the second physical quantity, and the customization unit then converts the second normalized physical quantity back into the second physical quantity by using the interconversion API and then sends the second physical quantity to the external device.