An information display system, which displays information suitable for each browser requiring information in a specific place, includes: a display device etc. which transmit signals via electromagnetic waves; and a portable terminal. The portable terminal includes: a reception measurement unit that receives the signals from the display device etc. and measures intensity of the signal; and a portable-device transmission unit that transmits predetermined data and intensity data indicating a measurement result. The display device includes: a display-device transmission unit that repeatedly transmits the signal via electromagnetic waves; and a display unit that changes a display state according to the data transmitted from the portable terminal. The display unit changes the display state to a first state where display information is displayed according to the predetermined data, when the intensity is greater than a first threshold, and changes a value of the first threshold after the change of the display state.