A built-in heating cooker which features both good cooling performance and effective countermeasures against spilled liquids by preventing ingress of water into the cooker body with a simple ventilation structure. This built-in cooker comprises a top plate where a pot and the like are placed, a support for supporting the top plate from underneath, a top frame covering the edge of the top plate and a frame constituting the cooker body. The support has a cooker-supporting face for supporting the cooker, and this is positioned outside of the top plate-supporting face. A first opening is provided on at least one side wall provided between the top plate-supporting face and the cooker-supporting face. A second opening is provided on a frame in a position corresponding to the first opening.