A process for preparing a polyhydric alcohol according to the invention comprises subjecting a polyhydric alcohol compound having protected hydroxy group(s) to microwave irradiation in the presence of basic compound(s) or acid(s) having an acid dissociation exponent (pKa) of −8 to 3 at 25° C. to remove the protecting groups of the hydroxy group of the polyhydric alcohol compound. The invention can provide an industrially advantageous process for preparing polyhydric alcohols by readily removing protecting group(s) from protected hydroxy group(s) of polyhydric alcohol compounds.