In the present study, rotating bending fatigue tests have been carried out in three kinds of carbon steel specimens; an annealed low carbon steel, an annealed high carbon steel and quenched-tempered high carbon steel; with a small artificial surface defect that might exist in real structures. Fatigue crack lengths have been observed by a method of replication in order to investigate the growth characteristic of fatigue crack in the viewpoints of strength of materials and fracture mechanics. The main results obtained are as follows: 1) The effect of a small surface defect upon the reduction of fatigue limit is considerably large, and the rate of fatigue limit reduction grows in the following order; annealed low carbon steel(mild steel), annealed high carbon steel, quenched-tempered high carbon steel. 2) When the growth rate of surface crack length(2a) was investigated in the viewpoints of fracture mechanics based upon $ ${Delta}K_{varepsilon}$</TEX>, the dependence of stress level and of surface defect size disappear, and there exists a linear relationships between d(2a)/dN and ${Delta}K_{{varepsilon}t},;Delta_{{varepsilon}t}sqrt{{pi}a}$, on log. plot, i.e, $d(2a)/dN={C{cdot}{Delta}K_{varepsilon}}^3_t$, where ${Delta}_{{varepsilon}t}sqrt{{pi}a}$ a is the cyclic total strain intensity factor range.