The present invention relates to an ink composition and a writing instrument. The ink composition comprises 10 to 70 wt % of a metallic pigment, 10 to 30 wt % of a resin, 0 to 20 wt % of a colorant, 0 to 20 wt % of an auxiliary agent and a solvent as the remainder; the solvent is a main solvent or a mixture of the main solvent and an auxiliary solvent; the resin includes a film-forming resin and a thickening resin; the present invention uses a low-level monohydric alcohol solvent as the main solvent, a polyvinyl acetal resin as the film-forming resin, and further includes the auxiliary agent, the metallic pigment or the colorants, so the ink composition with such good characteristics as being environmental friendly, drying quickly, being written smoothly and having strong compatibility to general writing surfaces is produced.