Provided are a design assistance device, a design assistance system, a server, and a design assistance method that displays shapes and specification information of plural items included in an item group so that a user can easily view the items. The design assistance device includes: a three-dimensional data acquisition unit that acquires three-dimensional data of an item group including a plurality of items; a display data generation unit that generates two-dimensional display data including a two-dimensional display representing an appearance of the item group and specification information of at least one of the items in one observation direction in the three-dimensional data; and a display mode determination unit that determines a display mode of the specification information in the two-dimensional display based on a shape of each of the items as well as relative positions and relative orientations between the items as viewed in the one observation direction.