A machining apparatus that need not exchange a processing nozzle when changing a shaping condition, and increases the use efficiency of a material. The processing nozzle that performs processing by ejecting a processing material towards a molten pool formed on a process surface by an energy line includes a cylindrical inner housing that incorporates a path through which the energy line passes, and ejects the energy line from one end. The processing nozzle also includes a cylindrical outer housing that incorporates the inner housing, and has an inner surface tapered in the ejection direction of the energy line ejected from the inner housing. The processing nozzle also includes a slide mechanism that changes, along the energy line, the relative position of the outer housing with respect to the inner housing.