The invention relates to an optical device such as an optical low-pass filter, and a production method therefor, which prevents damage, and thus maintains optical characteristics. In the optical device of the invention, a plurality of optical plates are stuck together with adhesive. The adhesive is spread to span to the side face or the outer periphery of the principal plane surrounding the plurality of optical plates, to thereby form a protective coat. Moreover the production method for an optical device, for example an optical low-pass filter, of the invention, where a plurality of optical plates are stuck together with adhesive, involves; spreading an adhesive between principal planes of the plurality of optical plates; pressing the plurality of optical plates from both principal planes to overflow the adhesive from between the both principal planes; and effusing and spreading the adhesive to span to the surrounding side face or periphery of the principal plane to thereby form a protective coat.