The relates to a loading mechanism which can realizes a miniaturized, light-weight and thin magnetic recording/playback apparatus. A running path of a magnetic tape from a position where the tape leaves out of a rotary head cylinder to a capstan is settled merely with roller posts without any fixed post, whereby a tape running load is considerably decreased. Because the loci of movement of take-up and supply loading boats which are respectively guided along associated loading guides correspond to the loci of revolution of drive shafts fixed on loading rings at take-up and supply sides, the loading boats can be driven directly by the drive shafts, whereby a simplified loading mechanism can be achieved.