Dialkoxymagnesium granules having spherical or ellipsoidal particle shapes with a mean particle size, represented by D50, in the range of 60-200 μm, a bulk specific gravity of 0.2-0.7 g/ml, having numerous interior pores with pore sizes of 0.1-5 μm as observed with a TEM, and having a particle size distribution, represented by (D90−D10)/D50, of no greater than 1. Granular metallic magnesium and an alcohol are added continuously or intermittently in divided portions to a reaction system of the metallic magnesium and alcohol while circulating the alcohol for reaction. Large-sized dialkoxymagnesium granules are obtained with a uniform particle size distribution and containing no fine powder.