Abstract: A sheet feeding device for an electrophotographic copying machine and the like has a flapping up member which protrudes through the bottom of a sheet feeding cassette to bring the sheets thereon into contact with a sheet feeding roller. The flapping up member is moved by a driven lever which is in turn moved by a low-tension biasing member in the direction of flapping the bottom plate up upon receipt of a sheet feeding commencement signal. A restrain member energized by a high-tension biasing member is provided to restrain the flapping up member to the retreated position upon termination of the sheet feeding commencing signal whereby the sheet feeding cassette is not affected by any resistance at the time of insertion or removal of the cassette and the bottom plate of the cassette is automatically flapped up only while sheet feeding is being operated.