A novel amino resin composition prepared by reacting one or more of the triazine derivatives represented by general formula (I) with formaldehyde, wherein R?1, R2, R?3, R4, R5 and R6¿ are each independent, and one to five of them are each C¿1?-C20 alkyl, C2-C20 alkenyle (wherein the alkyl or alkenyl may optionally contain an alicyclic structure or a phenyl group in the structure, or alternatively, when two of the alkyl or alkenyl groups are bonded to the same nitrogen atom, both of them together with the nitrogen atom may form a 3- to 8-membered nitrogenous heterocycle) or phenyl, while the other(s) of them is hydrogen; another novel amino resin composition prepared by reacting a mixture comprising one or more of the above triazine derivatives and melamine and/or urea with formaldehyde; and still another amino resin composition comprising a novel amino resin composition prepared by reacting one or more of the above triazine derivatives with formaldehyde and one or more resins selected from among melamine resins, melamine-urea-formaldehyde resins and urea-formaldehyde resins. These amino resin compositions are excellent in tenacity and post-formability and have heat resistance, high hardness and excellent gloss which are inherent in melamine resins, so that they are usable for laminated sheets, decorative sheets, molding materials, and so on. Further, the compositions can be improved also in solubility in organic solvents and lipophilicity by selecting the substituents, and therefore are usable in the fields of paints, adhesive bonding of wood difficult of adhesive bonding, and so on.