PURPOSE: To obtain a flame-retarding phenolic resin which can give a resin laminate of excellent low-temperature punchability without detriment to electrical properties, etc., by adding a specified compound to the reaction system of a phenolic resin and reacting the mixture.

CONSTITUTION: A flame-retarding phenolic resin is produced by adding a compound of formula I to the reaction system for producing a resol phenolic resin. In formula I, R1 and R2 are each a 2W10C monovalent aliphatic or aromatic residue and R3 is a 2C or higher monovalent aliphatic or aromatic residue. An example of the compound of formula I includes a compound of formula II. The most excellent effect can be obtained by adding the compound of formula I when a phenol is reacted with an aldehyde in the presence of a basic catalyst. The amount of the compound of formula I used is 2W30wt% based on the phenol feed.