1. An image processing device comprising: a memory; and a processor coupled to the memory and configured to: execute a first estimation process including detecting a marker having a predetermined shape from a captured image obtained from a camera, and estimating first position and posture of the camera at a time when the captured image is captured, based on a shape of the marker, execute a second estimation process including obtaining a map point in a three-dimensional space from the memory, and estimating second position and posture of the camera at the time when the captured image is captured, based on a correspondence between a projection point in which the map point is projected on the captured image and a characteristic point extracted from the captured image, and select the first position and posture or the second position and posture based on a result of comparison between a first translational component of the first position and posture and a second translational component of the second position and posture.