Provided is an electronic controller which enables visual identification of a portion applied with a small amount of a sealing material, which has a high possibility of air leakage from an area in which a joint is to be established. The electronic controller includes: an electronic circuit board; and a casing including a cover (1), a base (4), and a lid sealed with a sealing material (20) applied to surfaces thereof at which the cover (1), the base (4), and the lid are to be joined together. An area in which the cover (1), the base (4), and the lid are to joined together is provided with a space (16) thereto for enabling an application state of the sealing material (20) to be observed with a naked eye.