A bottle cap that is an apparatus for containing heterogeneous materials, applied in the discharge direction of materials in a container, comprises: a main body coupled to a bottle neck; and a containing unit assembled inside the main body with a storage space. An activated unit is assembled in the center of the upper support unit of the main body. An activation unit for downward movement is coupled to the activated unit so that the activated unit may move downward by a separate activation unit. An opening/closing unit is coupled with the lower part of the activated unit with the above structure in order to seal an opening/closing hole of the storage space.