Muonic hydrogen is a bound state of a proton and a negative muon. It is an ideal system to study the bound-state QED effects and atomic scale phenomenon.When a muon stops in gaseous hydrogen, muonic hydrogen forms in highly excited states. The muonic hydrogen will be de-excited to the ground-state by several cascade processes such as the radiative transition, external Auger effect, Stark mixing, and Coulomb de-excitation. The proposed experiment aims to reveal the nature of cascade processes by measuring the muon spin polarization and the space-time distribution of muonic hydrogen. The pulsed negative muon beam irradiates a gas cell filled with hydrogen at 0.1 atm. A transverse magnetic field of 667 Gauss will be applied by using the magnet of CHRONUS spectrometer at RIKEN-RAL Port4. Decay electrons from muonic hydrogen atoms will be detected muon spin rotation will be observed.