To provide a tank traffic device for a tanker that has improved safety.

In the tank traffic device provided with ladders in a tank includes a frame 51 provided on the tank top 7, stages 53, 55, 57 provided inside of the frame 51 at prescribed intervals, and inclined ladders 59, 61, 63 connecting the stages 53, 55, 57 in order. Since the frame 51 is provided on the tank top 7, a stage 67 for a vertical ladder is also fixed in a hanging structure to a deck 19 through a vertical ladder 49, and the stage 67 for the vertical ladder and the stage 53 are connected by an inclined ladder 69, there is no connection with a corrugated lateral partition wall 15. Thus, a structure capable of preventing cracks in ladders can be achieved.