In the High Field Laboratory for Superconducting Materials at Tohoku University, we have built up in the last four years three hybrid magnets capable of 30 T, HM-1, HM-2, and HM-3. Two of these magnets, HM-3 (32 mm bore, 20 T) and HM-2 (52 mm bore, 23 T) have been already made available for the development of superconducting materials for nuclear fusion reactors. The outer, superconducting, parts SM-3 and SM-2 of these magnets, wound with multifilamentary NbTi conductors, can both generate 8 T and have the room temperature bores of 220 and 360 mm, respectively. The fabrication of HM-1, the maximum field of which had been designed to be either 31 T (32 mm bore) or 29 T (52 mm bore), was finished last spring and we succeeded in generating 30. 7 T on May 29, 1985. A 12-T superconducting magnet (SM-1) with a room temperature bore of 360 mm was used in HM-1. SM-1 used Ti-doped Nb//3Sn multifilamentary conductor. The design, construction, test and operation of these three superconducting magnets are reported in detail. A few examples of H//c//2 and J//c measurements in HM-1 are also presented.