A process for producing a phosphonitrilic acid ester. The process comprises using a specific compound as a catalyst to react phosphonitrile dichloride with at least one member selected among phenol compounds and/or alcohol compounds in the presence of a reaction solvent. Alternatively, the process comprises reacting a liquid reaction mixture obtained in a first stage with at least one member selected among phenol compounds and/or alcohol compounds without isolating phosphonitrile dichloride from the mixture.
