The purpose of the present study is to analyze the effect of surface roughness on fatigue life of center-link chain made by SCM440 steel. Two groups of specimens were made from SCM440 steel with and without surface polished after forging process and resulted in different values of surface roughness. The difference of the surface roughness between two groups was clearly distinguished even to the naked eye. The surface roughness of both groups of the specimens was quantitatively measured by a roughness measuring device, Talysurf series2 (Taylor-Hobson Co., USA). Average roughness (Ra) values were obtained by scanning 45 mm with a speed of 0.25 mm/s. Fatigue tests were conducted using a three-point bending method with a cyclic sinusoidal profile of 5 Hz, stress ratio of R = 0.1 and reference life for fatigue limit of 1 × 10^6 cycles. Ra without surface machining was 10.5 ± 1.7 μm, respectively while those values with surface machining were 0.9 ± 0.5 μm. It was found that the average roughness decreased approximately 12 times compared to the testing specimens without surface machining. The results of the fatigue test using the specimen with reduced surface roughness (from Ra = 10.5 to 0.9 μm) by surface machining demonstrated reduced scattering and increased fatigue limit (from 746.7 to 920.3 MPa). The results showed that an increase in surface roughness values led to a decrease in fatigue lives.