To assure an improvement in the durability and stable operation performance of a guide display device by making it possible to efficiently dissipate the heat generated in power source units housed in the device installed in the premises of a station, etc.

A casing housing a display and a drive control circuit is provided with a tubular vent path 9 which penetrates the inside of the casing from a base plate to a ceiling and is opened at both ends to the outside of the casing. Heat radiation fins 6 of the power source unit 5 are projected within the tubular vent path 9. Isolation plates 10 and 11 which are projected from the inner side of the tubular vent path and are disposed with the front ends facing the flanks of the heat radiation fins and isolation plates 12 which project from the root side of the heat radiation fins and are disposed with the front ends so as to face the top surfaces or under surfaces of the isolation plates 10 and 11 are arranged apart suitable intervals alongside the respective heat radiation fins 6. The outdoor air flowing into the tubular vent path 9 is convected while this air is made to meander between the heat radiation fins 6 and the isolation plates 10, 12 and 11.