To prevent leakage of client information or working information.

Concerning the information providing device for amusement places, a server 10 transmits client information 14 to clients 40a, 40b,..., 40z and transmits information designated in information to be managed to an information receiver 20. Each of clients 40a, 40b,..., 40z deciphers the client information 14 received from the server 10 and transmits worked and enciphered working information 16 to the server 10 on the basis of the deciphered client information and its own client information 42a, 42b,..., 42z. The information receiver 20 deciphers the designated information received from the server 10. Since the client information 14 and the working information 16 are enciphered during transmission/reception between the server 10 and each of clients 40a, 40b,..., 40z and management due to the server 10, so that the leakage of these information contents can be prevented.