The extent and area of seabed swept by fishing gear is necessary information to examine the effects of the fishing on the seabed. We estimated the gear footprint of fly-dragging fishing gear which has not been well studied until now, by measuring its movement. We installed a GPS logger on the fishing boat (80 kW main engine) to determine the its speed and track, acoustic transponder loggers with depth gauges on the heaviest part of the warp (300 m from the boat of the total 712 m in length, called elbows) to determine the distance between the elbows, depth loggers on the head rope and on the ground rope to determine the water depth and the net height, underwater tension loggers connected to the bridles to understand when the tension was transmitted, and speed loggers on the top of the net to determine the speed of the net. Four hauls ranging from 38.6 to 49.6 min from shooting of the marker buoy to retrieval of the net were done. The average distance between the elbows was 302.3 m at the start of the tow, which narrowed to 6.3 m at the end of the tow. The net began to move approximately 3.5 min after the start of the tow, and the speed of the net also increased as the elbow narrowed and the tension increased. The gear footprint which is the area of seabed where either warps or the net passed over was 200,978 m2 on average, which was much larger than the estimated gear footprint of other Japanese demersal towed net that use similar sizes of boats and nets. Demersal seine fishing including the fly-dragging use light and small fishing gear so that it is considered as an ecologically-friendly fishing method compared to otter trawls, but the large gear footprint as estimated in this study may give a negative impact on the seabed environment since the gear would shear off sessile organisms and seaweeds, and flatten the seabed.