1. A radar device comprising: a signal vector-forming unit configured to form signal vectors having elements of a number of N based on waves reflected from an object and received by using a plurality of receiving antennas of the number of N; a submatrix-forming unit configured to (i) calculate N×N covariance matrices based on the signal vectors having the elements of the number of N, (ii) extract N×(N−1) submatrices from the N×N covariance matrices, and (iii) form two of (N−1)th-dimensional submatrices R 1 and R 2 from the N×(N−1) submatrices; a regular matrix operation unit configured to calculate a regular matrix Ψ as Ψ=R 1 −1 *R 2 from the two of (N−1)th-dimensional submatrices R 1 and R 2 ; an eigenvalue decomposition unit configured to calculate an eigenvalue exp(jΦ k ) (k=1 to N−1) of the regular matrix Ψ; and an angle calculation unit configured to calculate an angle θ k , at where the object is present from phase θ k =2*π*(d/λ)*sin(θ k ) of the eigenvalue exp(jφ k ), where d is a distance between antennas of a uniform linear array reception antenna, and λ is a wavelength of a center frequency of signals formed by an oscillator.