1. A radar device comprising: a signal vector-forming unit for forming signal vectors based on waves reflected from an object and received by using a plurality of receiving antennas; a submatrix-forming unit for forming submatrices based on said signal vectors; a regular matrix operation unit for calculating a regular matrix from said submatrices; an eigenvalue decomposition unit for calculating an eigenvalue of said regular matrix; and an angle calculation unit for calculating an angle at where said object is present from said eigenvalue.