The effect of uni‐axial cyclic mechanical stretch on the activation of the transcription factor nuclear factor κB (NF‐κB) was investigated in a human fibroblast cell line (TIG‐1). In response to uni‐axial cyclic stretch, NF‐κB was found to be translocated into the nucleus. The NF‐κB was first detectable 2 min after the onset of stretch and then peaked at 4 min and returned to the basal level within 10 min. To investigate whether NF‐κB is activated following the translocation into the nucleus, we measured the luciferase activity in the cells transfected with pNF‐κB‐luciferase. The activity of luciferase increased 4 min after the initiation of cyclic stretch, peaked at 15 min (6.4‐fold increase), and decreased gradually. We examined the involvement of the stretch‐activated (SA) channel in the stretch‐induced NF‐κB activation. The application of Gd³+, a blocker of the SA channel, or the removal of extracellular Ca²+ inhibited both the translocation into the nucleus and the activation of NF‐κB, which suggests that NF‐κB is activated by uni‐axial cyclic stretch via SA channel activation in human lung fibroblasts.