PURPOSE: To dispence with a protection net of accumulator of a hydraulic down-the-hole drill and improve response speed.

CONSTITUTION: In a tube body 11 a multi-pipe structure is provided. A working oil path 17 and an annular space concentrical thereto are formed. The annular space is divided into a gas chamber 19 and oil chamber 20 by means of bladder 18 and in a partitioning pipe 14 between the chamber 20 and the path 17 an oil hole 23 is bored. A plurality of distance rings 30 having uneveness formed on a contact face are continuously formed on the oil chamber 20 side of the partition tube 14 so that each contact face faces the oil hole 23. When working oil flows out from the oil chamber 20 the bladder 218 is not brought into pressure contact with the oil hole directly and thus no damage is generated and a sufficient oil path is formed with the uneveness on the contact face of the ring 30 thereby generating no disturbance on the flow of oil.