A radar device includes a transmission antenna, a reception antenna, and at least one of a circuit and a processor with memory storing executable code. The circuit or processor generates multiple coded transmit signals, and the reception antenna receives a mixed signal formed by reflections. The circuit or processor acquires the mixed signal from a specific reception antenna and generates decoded signals for the respective codes. A removal process estimates a sidelobe component detected in another decoded signal in correlation with a target component corresponding to a selected transmit signal, removes the estimated sidelobe component from a specific decoded signal or an associated related signal, and sets the correlation target after a previous removal as the target component. The device determines the number of removal executions based on a peak-to-thermal-noise ratio and repeats the removal accordingly.