A device capable of acquiring a deviation of a working position of a tool with respect to a target position of a workpiece with higher accuracy in accordance with actual work. A device for acquiring a deviation amount of a working position of a tool with respect to a target position when a work is performed on a workpiece with respect to the target position by the tool, the tool being moved by a movement machine, the device including: a camera arranged in a predetermined positional relationship with respect to the tool and configured to image the target position at a first time point when the tool performs an operation for the work; and a deviation amount acquisition section configured to acquire a deviation amount between the working position and the target position at the first time point, based on a position of the target position in image data imaged by the camera and information indicating a position of the working position in the image data.