A support device for ergonomic support of a user's hand during operation of a hand-operated input device, such as a computer mouse. The device includes a left pad and a right pad, spaced apart by a hinge that enables the pads to fold into a closed configuration for transport or storage. The hinge may be a living hinge integrally formed with at least a portion of the left and right pads. The pads support the pisiform and trapezium regions of the heel of the hand, respectively, and are configured to slide on a work surface. The device may include a latching mechanism, such a magnetic latch, to releasably hold the device in the closed configuration when not in use.