Abstract: A housing unit for containing electronic equipment consists of a plurality of housings which are connectable one to another. Each independent housing has respective first intake and exhaust ports formed in opposite sidewalls as well as respective second intake and exhaust ports formed in the front and rear walls respectively. An air flow passage is formed between the first intake and first exhaust ports through the chassis of the equipment contained in the housing when one housing is used as a stand alone unit. The individual housings are so constructed to be connectable in a way that air flow passages are conveniently formed in each housing with a common partition wall between the passages.