A radar apparatus (1, 2, 3) for a vehicle travelling along a curve or turning, the apparatus comprising: a transmitter that is adapted to transmit a radar signal via a transmission antenna mountable on a side of the vehicle; a receiver that is adapted to receive one or more reflected wave signals via a receiving antenna mountable on a side of the vehicle, the receiving antenna including a plurality of antennas, the reflected wave signals being the radar signal reflected by one or more objects; a signal processing unit that is adapted to determine azimuths of the objects with respect to the radar apparatus, Doppler speeds between the radar apparatus and the objects, and intensities of the reflected wave signals by using the reflected wave signals; and a state estimation unit (20, 21) that is adapted to estimate a speed and a traveling direction of the radar apparatus using the azimuths of the objects, the Doppler speeds, and the intensities of the reflected wave signals, wherein the state estimation unit (20, 21) comprises: a calculation unit that is adapted to set a plurality of potential traveling directions of the radar apparatus and calculate a plurality of potential speeds of the radar apparatus corresponding to the potential traveling directions using the azimuths of the objects and the Doppler speeds; a voting unit that is adapted to assign the intensities of the reflected wave signals from the objects to a plurality of potential states, each of the potential states being a combination of a unit of the potential traveling directions and a unit of the potential speeds of the radar apparatus, wherein the units of the potential travelling directions are obtained by dividing a range of the potential travelling directions, and the units of the potential speeds are obtained by dividing a range of the potential speeds; and a determination unit that is adapted to determine, as the speed and traveling direction of the radar apparatus, a potential speed and a potential traveling direction corresponding to a potential state having the largest sum of the intensities of the reflected wave signals. a transmitter that is adapted to transmit a radar signal via a transmission antenna mountable on a side of the vehicle; a receiver that is adapted to receive one or more reflected wave signals via a receiving antenna mountable on a side of the vehicle, the receiving antenna including a plurality of antennas, the reflected wave signals being the radar signal reflected by one or more objects; a signal processing unit that is adapted to determine azimuths of the objects with respect to the radar apparatus, Doppler speeds between the radar apparatus and the objects, and intensities of the reflected wave signals by using the reflected wave signals; and a state estimation unit (20, 21) that is adapted to estimate a speed and a traveling direction of the radar apparatus using the azimuths of the objects, the Doppler speeds, and the intensities of the reflected wave signals, wherein the state estimation unit (20, 21) comprises: a calculation unit that is adapted to set a plurality of potential traveling directions of the radar apparatus and calculate a plurality of potential speeds of the radar apparatus corresponding to the potential traveling directions using the azimuths of the objects and the Doppler speeds; a voting unit that is adapted to assign the intensities of the reflected wave signals from the objects to a plurality of potential states, each of the potential states being a combination of a unit of the potential traveling directions and a unit of the potential speeds of the radar apparatus, wherein the units of the potential travelling directions are obtained by dividing a range of the potential travelling directions, and the units of the potential speeds are obtained by dividing a range of the potential speeds; and a determination unit that is adapted to determine, as the speed and traveling direction of the radar apparatus, a potential speed and a potential traveling direction corresponding to a potential state having the largest sum of the intensities of the reflected wave signals. a calculation unit that is adapted to set a plurality of potential traveling directions of the radar apparatus and calculate a plurality of potential speeds of the radar apparatus corresponding to the potential traveling directions using the azimuths of the objects and the Doppler speeds; a voting unit that is adapted to assign the intensities of the reflected wave signals from the objects to a plurality of potential states, each of the potential states being a combination of a unit of the potential traveling directions and a unit of the potential speeds of the radar apparatus, wherein the units of the potential travelling directions are obtained by dividing a range of the potential travelling directions, and the units of the potential speeds are obtained by dividing a range of the potential speeds; and a determination unit that is adapted to determine, as the speed and traveling direction of the radar apparatus, a potential speed and a potential traveling direction corresponding to a potential state having the largest sum of the intensities of the reflected wave signals.