1. A remote control device of a heat pump system useable to switch an operating state of the heat pump system, the remote control device comprising: a touch screen; physical keys provided separately from the touch screen, the physical keys including at least two function keys; and a common function setting part configured and arranged to assign a plurality of different common functions to the function keys, the touch screen being configured and arranged to display a plurality of touch keys displayed by words, graphics, or symbols associated separately with any of a plurality of set items, a number of the function keys being fewer than a number of the touch keys, the plurality of different common functions being stored in a storage part and utilized when the operating state is switched, and the common function setting part being further configured and arranged to allow a user to select any one of the function keys to which any one of the plurality of different common functions is to be assigned, to display the plurality of different common functions on the touch screen so as to allow the user to select any one of the plurality of different common functions, and to assign the selected common function to the selected function key.