An object in a virtual reality space is made perform complicated movements. A user (or a keeper) who controls an object (or a pet) in a virtual reality space enters a command at the client terminal of the user by means of chat operation. The entered command is sent to a server. The server has a table listing the relationship between commands and movements to be performed by the object in the virtual reality space. For example, the relation is between command "Jump" and movement of jumping. The server interprets the received command by referencing this table. The interpretation result is sent to the client terminal. On the client terminal, the object (the pet) in the virtual reality space performs complicated movements such as dancing according to the received interpretation result.