To provide a method for achieving the selection of the scanning frequency to uniformly scan a range of a scanning region.

In the scanning method which includes a deflector of oscillating in a first deflection direction and a second deflection direction independently of each other, and of changing directions of electromagnetic waves to be incident on the deflector and of reflecting the waves, and two-dimensionally scans a space by scanning of the electromagnetic waves that have been deflected by the deflector, a first oscillation frequency f1 and a second oscillation frequency f2 are used so that a ratio of a phase lead angle β in the first deflection direction and a round angle is an approximate irrational number in a time for one reciprocation of the deflector in the second deflection direction.