Liquefied n-butane is surely contained in LPG, however, it leaves a surplus now in Japan. The advantage of the usage of n-butane for a CI engine is the small generation of soot owing to its smaller number of carbon than that of the gas oil which is used usually. Therefore, it is very significant for the global environment to find the capability of the usage of n-butane for a CI engine. Then, the macroscopic and microscopic atomization characteristics of nbutane spray injected through a hole nozzle were detected in a quiescent pressurized atmosphere at a room temperature by means of the optical method. As a consequence, the clear information on the spray characteristics was obtained from the experimental results.