A contact includes a plate with a width that ranges from 0.1 mm or more to 1 mm or less, and a stress concentrated place, where a surface roughness (Ra) on the stress concentrated place is 0.2 μm or less. When samples whose surface roughness Ra is 0.040 μm, 0.080 μm, 0.120 μm, and 0.180 μm were used to study a number of repetitive fracture times, as the surface roughness Ra was smaller, the number of repetitive fracture times became larger. Particularly, it is found that the surface roughness Ra may be 0.200 μm or less in order to satisfy 3000 times as a number of operating times of the battery connector. Further, the surface roughness Ra may be 0.080 μm or less in order to satisfy 6000 times as the number of operating times when a safety factor is 2.