There is provided a secure remote access system in which a user accesses a server while performing encrypted communication from an indefinite client, thereby performing a task. By using a storage device having a built-in tamper-proof device as a user authentication device, it is possible to improve user-friendliness. There is provided a server-client system in which a storage device having an authenticated tamper-proof device is distributed to a user and the user connects the storage device to an indefinite client and operates the server at distance by using the authentication information in the storage device and an application. Thus, it is possible to improve the user-friendliness. As a result, it is possible to utilize the task performing function inside and outside the worksite and reduce the confidential information remaining in the client operated, thereby improving the security and user-friendliness during client use by the user.