Unique behaviors of electrochemiluminescence from a device consisting of ZnO nanorod (Cell-1) are reported. Cell-1 emitted more intense electrochemiluminescence than cell consisting of two flat electrodes (Cell-2). The onset potential at which the emission starts was 1.5 V for Cell-1, which was lower than 2.5 V for Cell-2. The unique behaviors were explained by asymmetric collision modes of emitting species (Ru-I and Ru-III) in the nanospace among ZnO nanorods and were characteristic to the ZnO nanorod array.