To improve the efficiency of merchandise sales registering processing in the whole store in congestion by operating an optimal merchandise sales registering processor newly.

When a sales register judgment means judges the existence of a customer and a stand-by customer judgment means judges that the number of persons making a line at a sales registering processor is large, a support request means outputs a support request signal and an operation guiding means guides the start of operation of a merchandise sales registering processor installed in a selling area designated by sales designation information 15 corresponding to selling place count information 21 the counted number of which is large among sales registering processors out of operation in response to the output of the support request signal.