An electrochromic device according to an embodiment comprises a transparent conductive layer, an ion storage layer, an electrolyte layer, an electrochromic layer, and a reflective layer or a transparent conductive layer, wherein the ion storage layer includes an iridium atom and a tantalum atom, wherein the electrolyte layer includes a tantalum atom, wherein the electrochromic layer includes a tungsten atom, wherein at least one of the tungsten atom of the electrochromic layer and the iridium atom and the tantalum atom of the ion storage layer is hydrogenated, wherein the reflective layer is non-porous.