Purpose] The purpose of this study was to clarify the activity of oblique muscles during the sitting.[Subjects] The subjects of this study were 7 healthy males, mean age of 30.9 years. [Methods] An electromyography telemetry system (MQ-8, KISSEI COMTEC) was used for the measurements, and fifteen electrodes were arranged over the left oblique muscle. We measured electromyograms of the oblique muscles during lateral weight transfer in the sitting position. [Results] No significant changes were shown by the relative values of the integrated electromyograms as the lateral distance of weight transfer increased. The values of the oblique muscles on the opposite side showed increasing values at all electrodes, and two electrodes over the internal oblique muscle showed significantly higher values. [Conclusion] The results suggest that elevation of the pelvis by the internal oblique muscle on the opposite side is important during lateral weight transfer in the sitting position.