PURPOSE: To obtain a melamine resin of improved bending processability without degradation of its heat and water resistance, by reaction, with a melamine-formaldehyde system, of a lower aliphatic alcohol, a cyclc lactam, and an aromatic sulfonamide under a specific condition.

CONSTITUTION: A reaction is carried out, at a pH of 5.7W6.9, between A) 1mole of melamine, B) 1.3W3.0mol of formaldehyde, C) 0.5W1.5mol of a lower aliphatic alcohol (e.g., an 1W2C alcohol), and D) 5W40 parts by mole of a compound such as a cyclic lactam [e.g., a lactam of formula (n is 2W7)] especially preferably - caprolactam. Subsequently, E) 0.1W0.6mole of an aromatic sulfonamide (e.g., benzenesulfonamide) is added to the reaction system, followed by carrying out co- condensation at a pH 7.5W10, thus obtaining the objective flexible melamine resin.

EFFECT: Giving good bending processability even at low femperatures.