Provided are a method, client and system for reservation access to a management server using a one-time password. A generated personal identification number (PIN) is transmitted to the management server when a reservation time comes. The management server generates a random number encrypted using the PIN and transmits the random number to the client. The random number encrypted using the PIN is received, the received random number is encrypted by a symmetric-key algorithm using a client secret key and is transmitted to the management server. The management server receives the random number encrypted using the client secret key, and decrypts the received random number using a server secret key and the PIN. A random number before the encryption using the PIN is compared with a decrypted random number, and access of the client is accepted if the two numbers are identical. Automatic access to a system employing a one-time password authentication method can be made through an arbitrary route according to previously reserved settings to perform information collection and to process specific functions in the case where a system manager is unable to directly access the system through a determined route because of temporal and spatial limitations.