Young’s double slit experiments represent the mystery of quantum mechanics. To explore the mystery, varieties of the double slit and cross-double slit experiments were performed. In this article, we show novel phenomena that the interference patterns of the double slit/cross-double slit experiments can be curved. The curvatures depend on the orientation of the diaphragms of the double slit/cross-double slit. Those experiments provide comprehensive data for developing/testing a theoretical model.