1. A computer system comprising: a client computer; a first management computer coupled to the client computer; and a second management computer coupled to the client computer and the first management computer, wherein the first management computer sends, to the client computer, first security policy information for controlling the operation of a security management program of the client computer, and rule information denoting a rule for creating second security policy information from a plurality of pieces of the first security policy information, wherein the second management computer sends, to the client computer, other first security policy information in which the control operation differs from that of the first security policy information sent to the client computer from the first management computer, and wherein the client computer creates, on the basis of the rule information received from the first management computer, the second security policy information from the first security policy information received from the first management computer and the other first security policy information received from the second management computer, and controls the operation of the security management program based on the second security policy information.