PROBLEM TO BE SOLVED: To provide a device that does not require excavation of soil covering a culvert drain pipe, in a construction for washing and removing soil and sand deposited in the culvert drain pipe.SOLUTION: In a washing device for a culvert drain pipe, position detecting means which is inserted through into the culvert drain pipe buried under the ground to measure a laying position of the culvert drain pipe detects a position of soil and sand deposited in the culvert drain pipe, excavation means provided in an excavation rod opens the culvert drain pipe by contacting the excavation rod to the culvert drain pipe from a surface of the ground just above the position where the soil and sand are deposited in the pipe, for inserting the excavation rod into the culvert drain pipe, then high-pressure washing water is injected from an injection port provided at a distal end of the excavation rod positioned in the culvert drain pipe so as to remove the soil and sand deposited in the culvert drain pipe.
