Gallium and germanium porphyrin complexes in the lowest excited triplet (T-1) state have been studied by time-resolved electron spin resonance (TRESR). It is found that for Ge(TPP)(OH)(2) (TPP = dianion of tetraphenylporphyrin) intersystem crossing (TSC) from the lowest excited singlet (S-1) state to the T-1x and T-1y sublevels is faster than that to the T-1z sublevel (T-1x, T-1y, and T-1z are sublevels of the T-1 state), while the LSC of ZnTPP and Ga-(TPP)(OH) is selective to the T-1z sublevel. This is interpreted by a weak interaction between the d(pi) orbital of germanium and LUMO (e(g)) of the porphyrin ligand, resulting in small spin-orbit coupling (SOC). The interpretation is supported by molecular orbital calculations. The ISC of Ge(OEP)(OH)(2) (OEP = dianion of octaethylporphyrin) and Ge(Pc)(OH)(2) (Pc = dianion of tetra-tert-butylphthalocyanine) is found to be selective to the T1; sublevel in contrast to Ge(TPP)(OH)(2). This dependence on the porphyrin ligand is reasonably explained by a difference between the (3)(a(1u)e(g)) (the OEP and Pc complexes) and (3)(a(2u)e(g)) (the TPP complex) configurations. This is the first observation of a difference in selective ISC between the (3)(a(1u)e(g)) and (3)(a(2u)e(g)) configurations. The TRESR spectrum of Ge(TPP)Br-2 is different from those of Ge(TPP)CI, and Ge(TPP)(OH)(2), and is interpreted by SOC between the T-1 and T-2 states. From ESR parameters the square of the coefficient of the e(g) orbital on bromine is evaluated as 0.018 in the T-1 state.