A position detection device includes: a region acquiring unit that acquires a region where at least two of spheres with receiving antennas as centers and distances between each receiving antenna and a capsule endoscope as radii overlap with one another an orientation estimating unit that estimates orientations of the capsule endoscope at points in the region based on positional relationships between the points and the receiving antennas, and received strength of signals received by the receiving antennas and a position determination unit that determines the position of the capsule endoscope based on the positions of the points and the orientations, wherein the position determination unit calculates theoretical values of the received strength at the points, acquires measured values of the received strength at the receiving antennas, and detects a point having a minimum error between the theoretical value and the measured value as the position of the capsule endoscope.
