An operation assistance device includes a processor that executes a procedure. The procedure includes acquiring an operation image captured at each unit of operation in a linking operation to link a plurality of devices together, identifying positions, in the acquired operation image, of connection portions respectively provided at the plurality of devices, based on marker information included in the operation image, and based on design information of the plurality of devices, the design information including position information and a linkage state of the connection portions, executing image analysis processing on the identified positions of the connection portions to determine state of each connections made at each of the units of operation, based on a result of comparing a design image generated based on the design information and the operation image, and outputting information indicating a determination result to a display section.