A computer system includes multiple computer modules each including at least a calculator and a storing unit. A first computer module of the computer modules includes: a storing unit that stores authentication information for connection with a second computer module of the computer modules; an authenticator that authenticates an information processing device accessing the first computer module, and allows the information processing device to access thereto based on an authentication result; and a relay connector that connects the information processing device allowed to access the first computer module to the second computer module based on the authentication information.