Provided is an elevator group control system which is excellent in convenience and can prevent a decrease in operation efficiency even when an elevator is used by a group of a plurality of persons. For this purpose, there are installed in an elevator hall a destination operating panel by use of which users register their destination floors before boarding and a group boarding registering device for registering that users use an elevator as a group. The number of users expected when users use an elevator as a group is stored beforehand in a user head-count storage section. When registration of a destination floor by use of the destination operating panel has been performed at the same time with registration of a group use by use of the group boarding registering device, a car to be assigned to a hall car call is determined on the basis of the number of users stored in the user head-count storage section.