An interior base material is obtained by a method comprising a step of treating with a treating agent which comprises (A) a water-insoluble water-absorbent resin having a water absorbency to pure water for 50 to 1,000 ml/g and a particle size of 0.1 to 100 .mu.m, (B) a polyoxyalkylene nonionic surfactant and/or an anionic surfactant, and (C) a solvent having the boiling point of 50 to 250.degree. C. A process for printing the thus-treated interior base material comprises applying a dye ink having a viscosity of 1 to 100 cps by an ink-jet method, or applying a textile printing dye paste having a viscosity of 100 to 10,000 cps by a textile printing method followed by a heat-color developing treatment. The present invention provides a printed object with excellent sharpness, penetration effect enabling uniform printing from the surface to the deep part of the base material even to a base material having a thick three-dimentional structure or a base material having a long pile and thickness such as moquette, with an excellent build-up.