African swine fever (ASF) is a hemorrhagic infectious disease of Suids, which is endemic in sub-Saharan area of African continent. ASF is usually circulating sub-symptomatically among wild species of Suidae family, such as warthogs and bush pigs, by mediating Ornithodoros soft ticks. Domestic pigs (Sus scrofa) are, however, highly sensitive to the infection and show severe clinical signs with a high mortality rate, resulting a huge impact on pork production. Currently, there is no treatment or vaccine available. The etiological agent, ASFV, is highly resistant to environmental conditions, and resides in unheated pork meat or pork meat products for a long period, which may be a chance of its long-distance spread. Since August 2018, ASFV has been circulating in East and Southeast Asian countries and may possibly be introduced into Japan. Here, I describe the outline of the disease and the etiology of the pathogen in order to remind the importance of "awareness" and "preparedness" for the disease.