An image display system comprising two display units and a base unit for supplying image signals to at least one display unit and being capable of two-way communication with the other display unit. The image display system (1) comprises a portable display unit (100), a base unit (200) and a large-screen display unit (300), the base unit (200) supplying image signals to the display units (100), (300). The portable display unit (100) is provided on its display screen with a touch panel for detecting a position at which the user touches, a remote control panel RP to receive an input operation bythe user is displayed on the display screen, and an operation signal according to the display item of the remote control panel RP displayed at a touch position detected by the touch panel is formed and is sent to the base unit (200) in the form of wireless communication; while the base unit (200) selects an image signal supplied from an external input unit (400) as an image signal supply source according to an operation signal, for supplying to the large-screen display unit (300).