The invention is directed to the provision of an optical device in which provisions are made to form a gap between an optical waveguide and a substrate without having to form a groove or the like in the substrate and to prevent any stress from being applied to an optical element even when it is heated by a heater for temperature adjustment. More specifically, the invention provides an optical device includes a substrate, an optical element with an optical waveguide formed in a surface thereof that faces the substrate, bonding portions formed on the substrate at positions that oppose each other across the optical waveguide, a heater, formed on at least one of the optical element and the substrate, for heating the optical waveguide, and a micro bump structure formed from a metallic material, wherein the optical element is bonded to the bonding portions via the micro bump structure in such a manner that a gap is formed between the optical waveguide and the substrate.