[Problem to Be Solved] To provide a plant growth promotion device having a simple configuration, which can promote the growth of good tasting, high quality crops. [Means for Solving the Problems] A plant growth promotion device comprises: a flat-plate rotor 1 and a motor 2 coupled this rotor 1 by a rotary shaft 2a, wherein a plurality of permanent magnets 1 a are configured so as to be fixed in place at arbitrary intervals within the rotor 1, and the rotor 1 is rapidly rotated by the rotary shaft 2a that is coupled to the motor 2, so as to produce an alternating magnetic field in the surroundings of an agricultural field for crops.
