Comprehension of the turbulent burning velocity for lean hydrogen mixtures is inevitable in the improved design of hydrogen engines. The present study is performed to examine experimentally the turbulent burning velocity of lean hydrogen mixtures whose laminar burning velocity SL0 and equivalence ratio φ are varied extensively from 15 to 35 cm/s and approximately 0.9 to 0.3, respectively. The measured turbulent burning velocities at the same turbulence intensity show to increase as φ decreases until about 0.5. Those, however, does not show such increase when φ becomes lower than about 0.5, regardless of SL0. This phenomenon is discussed by the observation of turbulent flame structure and the estimation of Markstein number. The estimation of the mean local burning velocity of the turbulent flame is made also taking account of the preferential diffusion. It is found that their tendencies with φ is changed when φ becomes about 0.5.