PURPOSE: To obtain the titled substance useful as a raw material for a functional high polymer compound in high purity in high yield, by oxidizing a 2,6-bis(hydroxymethyl)phenol with MnO2.

CONSTITUTION: A compound shown by the formula I R is H, or 1W4C alkyl) is brought into contact with MnO2 in a solvent such as chloroform, acetone, ether, etc. at about room temperature for several hours W several days, to give a compound shown by the formula II. Active MnO2 obtained by thermal decomposition of manganese carbonate or manganese oxalate, or precipitation method from potassium permanganate and manganese sulfate, etc. is preferable as MnO2, and an amount of it used is 5W50 times as much as the compound shown by the formula I by weight.

EFFECT: After the reaction is over, the desired substance having practically sufficient purity is obtained simply by filtering the reaction solution to remove a Mn compound, followed by evaporating a solvent.