According to the present invention, differently from well-known production methods, with the use of a different starting material, Ullmann condensation which may decrease the yield with an increase of a production scale can be avoided and thus 6-amino-9-[(3R)-1-(2-butynoyl)-3-pyrrolidinyl]-7-(4-phenoxyphenyl)-7,9-dihydro-8H-purin-8-one can be provided safely and stably with high reaction yield.