An image analysis device comprising: an input interface to acquire image data indicating an image of an operator performing task; and a controller to detect the task performed by the operator sequentially, based on the image data, to generate task detection information indicating a detection result of the task, wherein the task includes a plurality of processes performed by the operator, and the controller compensates the task detection information by interpolating a detection result of the task within an undetected period, in accordance with a pre process and/or a post process of the undetected period, the undetected period being a period in which the task is not detected, the pre process being a process of the task detected previously to the undetected period, and the post process being a process of the task detected subsequently to the undetected period.