A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.

A print media holder device has first and second grip members. Permanent magnets are attached to the first and second grip members. An electromagnet is disposed between the first and second grip members, where when the electromagnet is selectively energized the permanent magnets attached to the first and second grip members are repelled in a manner that increases the outer dimension of the print media holder device to grip a media core.

A medium feeding unit that is configure to be mounted to an image forming apparatus provided with an image forming unit and feeds a medium to the image forming unit includes a medium introducing part that introduces the medium to the image forming unit and a medium holding part that holds the medium at a feeding position from which the medium is fed to the image forming unit. The medium holding part is configured to be positioned at one of at least two different feeding positions relative to the medium introducing part.