Abstract: According to one embodiment, a twin bit includes a main bit and an auxiliary bit. A carbide tip having a mountain shape protruding in an excavation direction is arranged at least on a top portion and a bottom portion that are located on a front end of a base portion of each of the main bit and the auxiliary bit. An apex portion of the mountain shape of the carbide tip of the auxiliary bit is located further behind an apex portion of the mountain shape of the carbide tip of the main bit in the excavation direction.

Abstract: An auger bit mounted on an auger head and having improved excavation efficiency is provided. The present invention is an auger bit 11 mounted on an auger head, the auger bit including: a base part 12 having a leading end protruding in an axial direction of the auger head; and two leg parts 13 and 14 continuously extending from the base part and facing each other at a predetermined interval, the base part includes a plane part 12a parallel to and continuous with planes of the leg parts, first tilted parts 12b to 12d that are tilted from the plane part toward a side closer to the leading end in the axial direction of the auger head, side surface parts 12e and 12f continuous with the first tilted parts, and a second tilted part 12g tilted from the first tilted parts toward a side closer to the leg parts in the axial direction of the auger head, and the plane part and the leg part each have a shape curved at a predetermined curvature relative to the axial direction of the auger head.