Abstract: A method of readily producing a gradient optical element having infrared absorbing ability by easily forming a refractive index distribution in a desired portion of a glass substrate having infrared absorbing ability without requiring a specific treatment atmosphere nor using a molten salt. More specifically, the present invention provides a method for producing a gradient-index optical element having infrared absorbing ability, the method comprising applying a paste containing an organic resin, an organic solvent, and at least one compound selected from the group consisting of lithium compounds, potassium compounds, rubidium compounds, cesium compounds, silver compounds, copper compounds, and thallium compounds onto a glass substrate containing an alkali metal component, at least one member selected from the group consisting of iron, copper, cobalt and vanadium, and over 3 wt.