An apparatus for assisting a setup work in a system having lines for producing types of products, each of the lines requesting the setup work for producing the product after switching of the type of product, includes a processor to calculate an earliest time when the setup work for each product in each line becomes executable based on the production-plan information, and when a difference between the earliest time when the setup work for a first product in a first line becomes executable and the earliest time when the setup work for a second product in a second line other than the first line becomes executable is equal or greater than a predetermined threshold value, determines that the setup work for the first product is executed before the setup work for the second product, and determines an execution order of the setup work for each product using a problem solver.