This　paper　deals　with　the　structure　of　essentially　disconnected　polyomino　graphs.　It　is　proved　that　for　an　essentially　disconnected　polyomino　graph,　the　normal　components　induced　digraph　is　acyclic　and　connected.　The　lower　bond　for　the　number　of　normal　components　of　an　essentially　disconnected　polyomino　graph　is　investigated.　Moreover,　the　essentially　disconnected　polyomino　graphs　with　two　or　three　normal　components　are　classified　and　constructed.