The Muon Science Laboratory at the Materials and Life Science Experimental Facility at J-PARC is now operating stably. In the first stage, a conventional superconducting muon channel was installed, which can extract low-energy positive muons (30 MeV/c) and medium-energy positive (or negative) muons up to 120 MeV/c. The established muon yield is several 10 7 /s for 60 MeV/c (both positive and negative muons) at a proton beam power of 1 MW. This channel is used for various experiments such as

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... spin spectroscopy, muon-catalyzed fusion and nondestructive elemental analysis. The superconducting solenoid is the key element of this beam line. We briefly present the construction and operation of this solenoid and cryogenics.