The present disclosure provides a hard-coating resin composition for a hard-coating having easy processability, flexibility and high surface hardness suitable for a hard-coating agent, in which a siloxane molecule having an inorganic material characteristic is chemically bonded with an epoxy group having an organic material characteristic to form one molecule, and the siloxane molecule is made to contain a various molecular weight distribution for dense crosslinking during polymerization of the epoxy group in order to obtain high surface hardness due to the inorganic material.