Coordination processing execution method and coordination processing execution system

Provided is a coordination processing execution method that is carried out using a plurality of household appliances and that can improve ease of use for a user over the prior art. The coordination processing execution method is for executing coordination processing using a plurality of household appliances that are registered on a server. The server maintains: one or more groups that are associated with specific processing executed by one of the household appliances and that are configured from one or more of the household appliances; and correspondence information indicating the correspondence with a control signal that is to be transmitted to each of the household appliances belonging to each group. The coordination processing execution method comprises: a detection step in which it is detected that specific processing was executed by a household appliance; a selection step in which the correspondence information is consulted when detection has occurred, and a group that is registered on the server and tha