Provided are a data relatedness assessment device, a data relatedness assessment method, and a recording medium that stores a program, which calculates relatedness between two or more pieces of data relevant to a task of a worker. A display area acquirer (13) acquires display area information that denotes respective display areas of two or more pieces of data displayed on the screen of a display (3). A line of sight information acquirer (11) acquires a line of sight position that is the position of the line of sight of a worker on the screen of the display (3). A gazing data generator (14) generates gazing data information that denotes data that the worker is gazing at based on the line of sight position and the display area information. An operation information acquirer (16) acquires operation information that denotes a content of an operation that the worker has executed on the displayed data. A data relatedness calculator (18) calculates mutual relatedness between the two or more pieces of data in the task of the worker according to a predetermined rule based on the gazing data information and the operation information.