An advertisement display device displays an outdoor advertising image and emits light (advertisement ID light) modulated in accordance with the advertisement ID and having the luminance changed temporally in the same direction as the display direction of the outdoor advertising image. Receiving the advertisement ID light, a portable terminal demodulates and decodes it to acquire the advertisement ID and sends advertisement recognition information including the advertisement ID, time, location of the portable terminal, direction from the portable terminal to the advertisement display device, and terminal ID to a server. The server aggregates the advertisement recognition information for each advertisement and for each time window and creates advertising effect information.