Abstract: Disclosed is a distribution system of contents, comprising a distribution server 4 stored with a content having a management file and a plurality of stream files with different data amounts and a player apparatus 1 for downloading the content via a communication line 5 and starting playback of the content during the downloading. The player apparatus comprises a detector unit 16 for detecting a transmission speed through the communication line, a selector unit 17 for selecting a stream file with a data amount depending on the transmission speed from the plurality of stream files with different data amounts, a stream file memory unit 14 for downloading and temporally memorizing the selected stream file, and a volume adjuster unit 15 for adding a padding data such that the data amount of the stream file becomes equal to a data amount specified in the management file when the data amount of the stream file is different from the data amount specified in the management file.