A motor driving circuit (100-1 to 100-3), formed by an integrated circuit, for driving a motor comprising: a second driver circuit for driving a driver circuit which is configured to supply a drive current corresponding to one phase of a multiphase motor having three or more phases, to the multiphase motor; and an electrical circuit which includes a plurality of electrical components characterized in that the electrical circuit is configured to switch a connecting relation between the electrical components according to an operation mode (A, B, C) designated from outside the motor driving circuit (100-1 to 100-3), thereby providing a circuit function corresponding to the operation mode; wherein the electrical circuit being a regulator including an oscillation circuit which outputs an oscillation signal, a voltage-dividing resistor, wherein an output voltage of the regulator is fed back to the voltage-dividing resistor, wherein the voltage-dividing resistor is configured to divide the output voltage that is fed back, an arithmetic unit which is configured to compare a voltage divided by the voltage-dividing resistor with a predetermined reference voltage (Vref 1212), a comparison circuit which is configured to compare a result of the comparison by the arithmetic unit with the output from the oscillation circuit, and a switching element which turns ON/OFF according to an output from the comparison circuit, and is configured to switch whether to use the output from the oscillation circuit or not, according to the operation mode, and thereby is configured to provide at least one of a switching regulator function and a linear regulator function as the circuit function corresponding to the operation mode, wherein the integrated circuit is formed as an N-chip configuration, wherein N represent the number of phases of the multiphase motor. a second driver circuit for driving a driver circuit which is configured to supply a drive current corresponding to one phase of a multiphase motor having three or more phases, to the multiphase motor; and an electrical circuit which includes a plurality of electrical components characterized in that the electrical circuit is configured to switch a connecting relation between the electrical components according to an operation mode (A, B, C) designated from outside the motor driving circuit (100-1 to 100-3), thereby providing a circuit function corresponding to the operation mode; wherein the electrical circuit being a regulator including an oscillation circuit which outputs an oscillation signal, a voltage-dividing resistor, wherein an output voltage of the regulator is fed back to the voltage-dividing resistor, wherein the voltage-dividing resistor is configured to divide the output voltage that is fed back, an arithmetic unit which is configured to compare a voltage divided by the voltage-dividing resistor with a predetermined reference voltage (Vref 1212), a comparison circuit which is configured to compare a result of the comparison by the arithmetic unit with the output from the oscillation circuit, and a switching element which turns ON/OFF according to an output from the comparison circuit, and is configured to switch whether to use the output from the oscillation circuit or not, according to the operation mode, and thereby is configured to provide at least one of a switching regulator function and a linear regulator function as the circuit function corresponding to the operation mode, wherein the integrated circuit is formed as an N-chip configuration, wherein N represent the number of phases of the multiphase motor. wherein the electrical circuit being a regulator including an oscillation circuit which outputs an oscillation signal, a voltage-dividing resistor, wherein an output voltage of the regulator is fed back to the voltage-dividing resistor, wherein the voltage-dividing resistor is configured to divide the output voltage that is fed back, an arithmetic unit which is configured to compare a voltage divided by the voltage-dividing resistor with a predetermined reference voltage (Vref 1212), a comparison circuit which is configured to compare a result of the comparison by the arithmetic unit with the output from the oscillation circuit, and a switching element which turns ON/OFF according to an output from the comparison circuit, and is configured to switch whether to use the output from the oscillation circuit or not, according to the operation mode, and thereby is configured to provide at least one of a switching regulator function and a linear regulator function as the circuit function corresponding to the operation mode, wherein the integrated circuit is formed as an N-chip configuration, wherein N represent the number of phases of the multiphase motor.