Seed shattering is an undesirable characteristic of rice cultivars affecting the loss of grain yield before and during harvesting. These grain losses are influenced by varietal characteristics. The histological peculiarities of the abscission region obtained were different among rice varieties, and had a close relationship with grain shedding. In order to obtain information for the breeding of new persistent shedding varieties, this study was designed to clarify the inheritance of grain shedding habits in relation to the abscission layer. In the cross combination of two easily shedding varieties, Milyang 23, a japonica-indica hybrid rice with cracked abscission layers and Ashahi, a japonica-type rice with uncracked abscission layers, the cracking of parenchymatous cells in the abscission layer was controlled by a single dominant gene. The breaking tensile strength coincided well with cracked and uncracked abscission layers. In four crosses between a persistent shedding variety without abscission layers and two easily shedding varieties with cracked abscission layers, and two medium shedding varieties with uncracked abscission layers, respectively, the formation of the abscission layer was controlled by a single dominant gene. The easily shedding and persistent shedding habits coincided well when the abscission layers were both present and absent. The easily shedding characteristics were dominant in cross combination. The close negative correlations were recognized between degrees of grain shedding and breaking tensile strengths.