Shield machine

A shield machine including an excavator capable of excavating tunnels of various cross-sectional shapes, the excavator including: a rotary drum supported at a front end side portion of a shield machine main body to be rotatable around a first center axis; a cutter supporting frame supported by the rotary drum to be rotatable around a second center axis; a rotary cutter head supported by the cutter supporting frame to be rotatable around a third center axis and including a plurality of cutter bits on a surface thereof; a rotary auxiliary cutter head supported by the rotary drum to be rotatable around a fourth center axis; and first, third, and fourth rotating mechanisms, and a swinging drive mechanism configured to respectively cause the rotary drum, the rotary cutter head, the rotary auxiliary cutter head, and the cutter supporting frame to independently rotate.