Disclosed is an eco-friendly water-based paint composition for interior finishing materials of buildings. The eco-friendly water-based paint composition includes: 3 to 6 wt. % of diatomite for adsorbing harmful materials; 7 to 12 wt. % of titanium dioxide for enhancing a deodorization effect; 0.4 to 1.5 wt. % of antimicrobial agent-containing microcapsules for killing harmful microorganisms derived from an indoor air; 0.1 to 0.5 wt % of preservative for suppressing and preventing propagation of fungi derived from indoor air; 30 to 40 wt. % of an inorganic binder for binding different ingredients of the water-based paint composition so as to form a smooth surface; 3 to 10 wt. % of water for blending different materials for the water-based paint and controlling workability; and residual silica for forming thickness during painting as a base material of the water-based paint.