A radar device including: a code generator (5,6) which generates a first code sequence and a second code sequence constituting a pair of complementary codes; a first modulator which modulates the first code sequence to generate a first transmission signal; a second modulator which modulates the second code sequence to generate a second transmission signal; a quadrature modulator (12 - 15) which performs quadrature modulation by using the first transmission signal and the second transmission signal that are generated by the first modulator and the second modulator, respectively; an amplifier which generates a high-frequency transmission signal from a signal that is quadrature modulated by the quadrature modulator (12 - 15); an antenna which transmits the high-frequency transmission signal from a transmission antenna; an RF receiver which converts a signal of the reflected wave that is obtained by reflecting the high-frequency transmission signal received by the reception antenna, from the target, to a base-band reception signal; a first correlation value calculator which calculates a first correlation value of the reception signal that is converted by the RF receiver, and a signal being identical with the first transmission signal that is generated by the first modulator; a second correlation value calculator which calculates a second correlation value of the reception signal that is converted by the RF receiver, and a signal being identical with the second transmission signal that is generated by the second modulator; and an adder which adds the first correlation value that is calculated by the first correlation value calculator and the second correlation value that is calculated by the second correlation value calculator, to derive a third correlation value; the radar device characterized by further comprising a signal reception extractor which extracts an IQ correlation value (AC(k pq)) which exceeds a preset threshold, from the third correlation value (AC(k)); an IQ multiplex interference component extractor which calculates an IQ multiplex interference component based on phase components (Θ(k pq)) of the IQ correlation values (AC(k pq)), wherein the IQ multiplex interference component is perpendicular to the peak direction (Θ(k pq)) of the IQ correlation value (AC(k pq)); and a subtracter which subtracts the IQ multiplex interference component that is calculated by the IQ multiplex interference component extractor, from the third correlation value to derive a fourth correlation value. a code generator (5,6) which generates a first code sequence and a second code sequence constituting a pair of complementary codes; a first modulator which modulates the first code sequence to generate a first transmission signal; a second modulator which modulates the second code sequence to generate a second transmission signal; a quadrature modulator (12 - 15) which performs quadrature modulation by using the first transmission signal and the second transmission signal that are generated by the first modulator and the second modulator, respectively; an amplifier which generates a high-frequency transmission signal from a signal that is quadrature modulated by the quadrature modulator (12 - 15); an antenna which transmits the high-frequency transmission signal from a transmission antenna; an RF receiver which converts a signal of the reflected wave that is obtained by reflecting the high-frequency transmission signal received by the reception antenna, from the target, to a base-band reception signal; a first correlation value calculator which calculates a first correlation value of the reception signal that is converted by the RF receiver, and a signal being identical with the first transmission signal that is generated by the first modulator; a second correlation value calculator which calculates a second correlation value of the reception signal that is converted by the RF receiver, and a signal being identical with the second transmission signal that is generated by the second modulator; and an adder which adds the first correlation value that is calculated by the first correlation value calculator and the second correlation value that is calculated by the second correlation value calculator, to derive a third correlation value; the radar device characterized by further comprising a signal reception extractor which extracts an IQ correlation value (AC(k pq)) which exceeds a preset threshold, from the third correlation value (AC(k)); an IQ multiplex interference component extractor which calculates an IQ multiplex interference component based on phase components (Θ(k pq)) of the IQ correlation values (AC(k pq)), wherein the IQ multiplex interference component is perpendicular to the peak direction (Θ(k pq)) of the IQ correlation value (AC(k pq)); and a subtracter which subtracts the IQ multiplex interference component that is calculated by the IQ multiplex interference component extractor, from the third correlation value to derive a fourth correlation value.