Photolysis of chloro(hydrido)(silyl)iridiumcomplex [Ir(Cl)(H)HMesSi(CH2)2PPh2}(PMe3)2] (1) caused the geometric isomerization to 2 which reached to a photostationary state with the ratio of 1 : 2 = 29 :71. Both 1 and 2 take mer configuration, but 1 has a hydrido ligand opposite to one of PMe3’s while 2 has that opposite to the PPh2. On thermolysis, 2 reverted to 1 quantitatively.