A cassette holder capable of being loaded with a radiation image capturing apparatus including a housing, a two-dimensional array of radiation detecting elements accommodated in the housing, and a connection port is shown. The cassette holder includes the following. Retention tabs hold the radiation image capturing apparatus. A connector is connectable to the connection port. The connector is magnetically fixed to the connection port. When the radiation image capturing apparatus is drawn to be detached from the cassette holder, the connector is movable with movement of the connection port. The movement of the connector moved with the connection port is regulated such that a shift distance of one end of the connector is smaller than a shift distance of the other end, and thereby the one end of the connector is detached from the connection port earlier than the other end.
