A working device is capable of moving inside a pipe, whereby it is possible to exert the extremely large driving force in the pipe, and provided the device for performing the work sufficiently such as the cleaning, the vacuum recovering, and the forcibly drying the wet internal surface of the pipe. The device which moves along the pipe and operates on the internal surface of the pipe, comprising: material feeding pipe, pressure boundary partition, pressure boundary seal, nozzle unit, material feeding hose, traveling device, feeding device of the surface processing material, vacuum generating means, negative pressure space, and environment pressure space. Wherein, negative pressure space and environment pressure space are defined in the pipe by pressure boundary partition and pressure boundary seal, and vacuum breaking valve mechanism maintains fixedly the differential-pressure between the negative pressure space and the environment pressure space, and which makes the environment fluid to flow into the negative pressure space from the environment pressure space.