Abstract: Disclosed herein is a wood-cased glass door assembly in which a glass door that may be opened is composed of a glazing, and wooden stiles and rails, which are fitted on an outer peripheral edge of the glazing. The wood-cased glass door is mounted for opening and closing into a wooden doorcase fixed in an opening in a wall. Thermally expanding materials are separately installed in spaces defined between an inner peripheral portion of the wooden doorcase and outer peripheral portions of the wooden stiles and rails and between inner peripheral portions of the wooden stiles and rails and the outer peripheral edge of the glazing over the entire length in the longitudinal directions of the spaces. The expanding materials foam and expand under heat to block the respective spaces. Metal fittings for holding the glazing by putting the inner and outer surfaces of the outer peripheral edge of the glazing therebetween are fixed to the wooden stiles and rails.