To efficiently display merchandise information at a low cost without using paper display means.

Merchandise information messages are stored together with merchandise information indicators to be unequivocally identified into the electric price tag addition data file 28 of a memory 24 of an electric price tag computer 12. In the case the merchandise information message is displayed on the electric price tag 14 associated with specific merchandise, the merchandise information indicator corresponding to the message is inputted to the record corresponding to the merchandise in a price retrieval (PLU) file 36. The control message addressed to the electric price tag is formed by reading the merchandise information indicator out of the PLU file and reading the corresponding merchandise information message out of the electric price tag addition data file 28. The control message is transmitted to the electric price tag and the merchandise information message is displayed on a display 22 of the electric price tag. There is no need for installing paper labels, price tags or handbills in order to send the information messages to customers.