The invention relates to an interior panel structure including first and second panels formed into an L-shaped panel structure and an L-shaped reinforcing member fixed to an outer corner portion of the L-shaped panel structure. The reinforcing member has a plurality of first through holes that are opposed to a minor face of the first panel. With this, it is possible to observe condition of the minor face of the first panel and remove major projections of the minor face. Thus, the interior panel structure is improved in external appearance.