PURPOSE: To prevent application of a deviated load on a ladder bearing during dredging, by a method wherein the ladder bearing of a bucket ladder is formed with a tranion, crossing perpendicularly to a horizontal shaft, and a horizontal shaft, and the tranion shaft is supported by means of a bearing device.

CONSTITUTION: A bucket ladder is formed with an auxiliary ladder 30, vertically rocked around a tumbler shaft 4 on a ship hull serving as a pivoting fulcrum, and a main ladder 20 elevatably slid along a slanted ladder well part 2 of a ship hull. The main ladder 20 is slid along the ladder well part 2. A horizontal bearing 25 of a main ladder elevation actuating body 10 is provided at its central part with a tranion shaft 26 crossing perpendicularly to the axis of the ladder, and the main ladder 20 is provided on its upper surface with a bearing device 27 supporting the tranion shaft 26. This enables prevention of application of a lateral load or an eccentric load on a ladder bearing during dredging.