A hole portion detection unit detects a hole portion of the bronchus from at least one of a first endoscope image or a second endoscope image temporally earlier than the first endoscope image. A first parameter calculation unit calculates a first parameter indicating the amount of parallel movement for matching the hole portions of the two endoscope images with each other. A second parameter calculation unit performs alignment between the two endoscope images based on the first parameter, and calculates a second parameter including the amount of enlargement and reduction. Based on the two parameters, a movement amount calculation unit calculates the amount of movement of the endoscope from the acquisition time of the second endoscope image to the acquisition time of the first endoscope image.
