Resin production method, resin produced thereby, and resin composition containing same

The present invention provides: a production method that makes it possible to obtain a high reaction yield of a resin in which the content of metal impurities is reduced and all or a part of phenolic hydroxyl groups are alkylated; a resin that is produced by the production method; and a resin composition that contains the resin. The production method is for producing a resin in which all or a part of phenolic hydroxyl groups are alkylated, and said production method includes a step in which a halogenated alkyl compound and a resin comprising a phenolic hydroxyl group are reacted under the presence of at least one organic base selected from the group consisting of tetraalkyl ammonium hydroxide compounds and nitrogen-containing compounds in which the acid dissociation constant of the conjugate acid is 12 or more.