The present invention provides a midget gas turbine has: a casing; an irregular-shaped hollow disk rotationally attached to a casing; said irregular-shaped hollow disk having in a hollow portion constituting a bursiform space having a closed peripheral portion in which a guiding vane is provided, and having a radius changing with respect to the circumferential direction; a fuel conduit provided from a central portion towards a portion of the outer peripheral portion of the irregular-shaped hollow disk and communicated with a fuel nozzle provided in the vicinity of the outer peripheral portion of the irregular-shaped hollow disk; and at least two combustion chambers each comprising a mixing portion for mixing a fuel injected from the fuel nozzle with an external air centrifugally compressed by the guiding vane, a combustor and a combustion gas discharge nozzle portion, said combustion chambers being provided at rotationally symmetric positions at the outer peripheral portion of the irregular-shaped hollow disk where the radius becomes maximum; wherein an external air taken in the hollow portion of the irregular-shaped hollow disk is compressed by the guiding vane, supplied to the combustion chambers, mixed with a fuel supplied from the fuel conduit to be burnt, and a combustion gas discharged from the combustion gas discharge nozzle is discharged towards a substantially circumferential direction of the irregular-shaped hollow disk, whereby the irregular shaped hollow disk is driven by the reaction of the combustion gas.