To output sounds generated by multiple objects disposed in a virtual space in as easy a manner as possible while giving live feelings, a storage unit (202) of a game machine (201) stores information on objects of a first type and a second type which move in the virtual space. A basic sound acquiring unit (203) acquires basic sound information corresponding to the total number of the objects. An imitation sound acquiring unit (204) acquires imitation sound information imitating a sound generated by an object of the first type from its position in the virtual space. A mixing output unit (205) mixes and outputs the basic sound information and the imitation sound information. An input receiving unit (206) receives an instruction input from the user. In a case where the instruction input satisfies a predetermined extinction condition, a deleting unit (207) deletes any of objects of the first type from the storage unit (202) if there is no object of the second type stored in the storage unit (202), and deletes any of objects of the second type from the storage unit (202) if there is.