There is provided an interface card system for SD bus control. The interface card system for SD bus control includes a CPU bus interface 11a and/or an SD bus interface 11b, a host interface module 16 connected to the interfaces which interprets an SD command and controls operation of the whole of the interface card system, first and second internal SD host engines 15a and 15b which function as a host controller, first and second selectors 14a and 14b respectively connected to the internal SD host engines which each select a path for data or a command, first and second SD bus interfaces 13a and 13b respectively connected to the selectors, and a data pass-through control section 17 connected to the SD bus interfaces connected to the selectors which allows an SD command and data to pass through.