A tube-leaky fiber that consists of only dielectric thin-film tubing for delivery of Er:YAG laser light is presented. The tube-leaky fiber confines light in the airy core when the film thickness is properly chosen for target wavelength. Transmission properties of the fibers are derived by using a ray optic method and designed the optimum wall thickness for the Er:YAG laser wavelength of 2.94 micron. In fabrication of the tube leaky fiber, we use a microstructural tube made of glass to enhance mechanical strength. The central bore and surrounding glass thin layer that is held by the microstructure function as a tube-leaky fiber. We fabricate a large-core fiber for delivery of high-power medical lasers by stack-and-draw method and we use borosilicate-glass as a fiber material for low cost fabrication. Fabricated fibers have a diameter over 400 μm and from the loss measurements for Er:YAG laser, and the fibers deliver laser light with a transmission loss of 0.85 dB/m that is comparable to 0.7 dB/m of conventional hollow-optical fibers. The fibers withstand transmission of laser pulses with energy higher than 120 mJ. We confirm that these energies are enough to ablate biological tissues in surgical operations.