The present invention discloses a process for producing a benzoxazine resin which comprises the steps of reacting a phenol compound, an aldehyde compound and a primary amine in the presence of an organic solvent to synthesize a benzoxazine resin and removing generated condensation water and the organic solvent from a system under heating and a reduced pressure, wherein a pressure in the reaction system at the time of removal is set to 260 mmHg or higher.