Why do wild boars cause agricultural damage? We analysed the behaviour of two wild boars that inhabited satoyama (agricultural woodlands and farmland) in Ohda City, Shimane Prefecture, Western Japan, to understand how such damage occurs and how to reduce it. We tracked the boars by GPS transmitter, recording their positions once per hour. Because we could not fit collars to the boars, we used a prototype vest-like garment, developed with the help of Teikoku Sen-i Co., Ltd. (Tokyo), which covered a boar from the shoulder to the chest. The boars were equipped with the devices in April 2005 and tracked for 12 and 15 days. Positional data and field surveys were used to ascertain boars’ use of the land. Bamboo forest and permanently abandoned farmland with emergent scrub were intensively used. Boars can find bamboo shoots, their main food, during early spring. The farmland was abandoned in the 1980s, 20 years before the investigation;kudzu grew abundantly, serving as food, and the land became a good habitat for feeding and resting. One factor behind boar-related damage appears to be their intensive usage of permanently abandoned farmland, which may expand to adjacent productive farmlands. To reduce boar-related damage, removing crops, fruit trees, and nutrient-rich surface soil from farmland before it is abandoned and from those that are already abandoned are necessary. Increasing numbers of abandoned farmland is a problem shared by developed countries because of population decline and aging. Therefore, a farmland management plan is important for reducing friction with wildlife.