A password is effectively prevented from being leaked to enhance the degree of security and, at the same time, can be input without difficulty. There is provided a removable information storage apparatus equipped with a predetermined interface for connecting itself to an external appliance and a security section with limited accesses from the external appliance, which includes a password input unit to be used that inputs a password of a predetermined number of words to be notified only to the information storage apparatus without being output to the external appliance connected to it by way of the predetermined interface, a password collating unit that collates the password input by way of the password input unit, and an access authorizing unit that authorizes an access to the security section from the external appliance connected to it by way of the predetermined interface in response to the collation of the password by the password collating unit. The password input unit is adapted to be used for inputting a password of not greater than a predetermined number of words as the password to be collated by the password collating unit, and the password collating unit is adapted to collate the password of not greater than the predetermined number of words input by way of the password input unit.