Composite music file is composed of a content section including a plurality of types of music content, and a header section including content type information of the plurality of types of music content. At least the content type information included in the header section is in a non-encrypted form. Once a composite music file is input, the content type information is read out from the header section of the input composite music file, and one usable music software is selected, on the basis of the content type information, from among a plurality of types of music software capable of reproducing the plurality of types of music content, so that the thus-selected music software is automatically started up.