A service linkage assistance device includes an executing unit which accepts a request for a stateless API for a stateful service which exposes a stateful API from a service linkage device which executes a linkage service obtained by linking multiple services including the stateful service, interprets the request, and executes the stateful API and a storage unit which stores dynamic information included in a response from the stateful API, and the stateless API is exposed to the service linkage device by the service linkage assistance device.