An interface device (15) is provided that includes an operating knob (30) for outputting an operation command signal to in-vehicle equipment, the operating knob (30) being provided with a palm rest portion (30a) for an occupant's palm to be placed on, and a switch (31) being disposed on the operating knob (30) within a region that a fingertip can reach while the palm is placed on the palm rest portion (30a). Since this determines the positional relationship between the switch (31) and the fingertip when the palm is placed on the palm rest portion (30a), even if the switch (31) is operated without being visually checked it is possible to prevent an erroneous operation from occurring and, moreover, the operability is remarkably improved. Furthermore, since tilting the operating knob (30), which is supported so that it can tilt in fore-and-aft and left-and-right directions, outputs an operation command signal to in-vehicle equipment, coupling this with operation of the switch (31) enables many types of operation command signal to be outputted.