In Japan, geophysical methods are normally used to estimate the distribution of cultural relics before digging. Objects of archaeological interest are usually located within a few meters of the surface. Therefore, geophysical methods suitable for archaeological exploration are those which provide high resolution at shallow depths. The most commonly used geophysical methods are ground-probing radar, resistivity, and magnetometry. Of these methods, we used mainly ground-probing radar and resistivity surveys in archaeological investigations at four sites. Three of the sites were in Gumma Prefecture (Japan); they were covered with volcanic deposits (loam or pumice). Using ground-probing radar, we were able to locate ancient dwellings, burial mounds, and a distribution of archaeologically significant "culture layers". At the other site, in Nara Prefecture, we located part of the remains of an ancient city. In this investigation, the resistivity method and ground-probing radar were combined to determine the location of an underground water course within the ancient city.