PURPOSE: A phenolic resin low in a formaldehyde content and capable of giving laminated sheets of excellent tracking resistance, obtained by adding urea in a specified weight ratio to formaldehyde to the reaction system for producing a phenolic resin.

CONSTITUTION: When producing a phenolic resin (e.g., tung oil-modified or melamine-modified phenolic resin) by reacting a phenol with formaldehyde, 1W20wt%, based on the formaldehyde used, urea is added to the reaction system. It is preferable that urea is added to the system just before or after completion of the dehydration reaction. It is possible to decrease free formaldehyde present in the reaction system for producing a phenolic resin and therefore to decrease free formaldehyde remaining in a laminated sheet produced from such a phenolic resin, with consequent improvement in its tracking resistance.