An apparatus for multicasting contents between devices in different networks includes: a home-to-home multicast control device for finding the devices in the networks, downloading contents from a device in a network to which the home-to-home multicast control device belongs, processing the contents to generate file blocks, each file block having chunk files, and multicasting the processed contents to the devices in the networks; and at least one home-to-home multicast bridge device for receiving the contents transmitted from the home-to-home multicast control device and streaming the contents to one or more devices in a network to which the home-to-home multicast bridge device belongs. The apparatus further includes a multicast relay device for relaying the contents between the home-to-home multicast control device and the home-to-home multicast bridge device.