To purchase a thing which the viewer thinks that he or she wants to buy while a program is on the air, it is necessary to take procedures, (1) searching for information and (2) placing an order (at a store), which requires trouble and time. With respect to, of the things used in a program, things which are objects of sale, data as recognition words and a merchandise tag are transmitted so that the recognition words or the merchandise can be narrowed down. The user specifies by voice a thing which he or she wants to purchase while watching a program. After watching the program, the user determines whether to purchase the merchandise specified while watching the program or not by perusing the merchandise and related information. The seller is notified of the registration of purchase through the broadcasting station, and it is facilitated to sell and purchase clothes, furniture or the like used in programs being broadcast.