[en] The time spectrometer for the measurement of magnetic fields, appearing on the μ-mesons in magnetic matters, and for the observation of the two-frequency muonium procession in large magnetic fields, is described. The spectrometer consists of the scintillation counter system (SCS) and electron apparatus. The SCS is placed within the electromagnet, creating 0-8 kOe field, perpendicular to the muon beam. The polarized muons from accelerator are halted in the target from the investigated matter. The muon stopage in the target and escape of μ-e--decay electrons are registrated by the SCS. Under working conditions with the scintillatof of 150x150x20 mm size the spectrometer time resolution equals 320 ps, differential non-linearity at the channel width 55 ps equals +-1%