A pair of parallel frame members 30 and 31 are formed in the inner bobbin faces of recording/reproducing and erasing coil assemblies 3, 4 on the opposite sides and spaced equidistant from a core tip center line T. An orthogonal frame member 32 is formed on the outer side of each of the bobbin end face to extend in a direction perpendicular to the parallel frame members 30 and 31. The end of the orthogonal frame member 32 extending toward an auxiliary sliding face 15 of a slider 2 extends outwardly from one of the parallel frame members 31. The recording/reproducing and erasing coil assemblies 3 and 4 are disposed asymmetrically to each other about the core tip center line T. When the recording/reproducing and erasing coil assemblies 3 and 4 are respectively housed in coil assembly receiving portions 26 and 27, the coil assemblies 3 and 4 will not extend outwardly beyond a slider plane projection line C.
