To provide an earth auger which can serve for improvement of work efficiency and accuracy (especially in vertical accuracy) in execution of work while reducing cost.

An auger rod 3 which is composed of an outer rod 6 having a strong rigidity and an inner rod 7 having a drilling screw head 9, an agitating blade 10 for agitating excavated soil and an extension blade 11 respectively at its front end part is provided. And a fixed blade 20 which protrudes in the direction right-angled against the axis of the auger rod 3 and shears and ruptures the excavated soil together with the extension blade 11 is provided. Furthermore, a plurality of drilling blades 9a are provided in projection for the drilling screw head 9 at specified intervals in the circumferential direction of the inner rod 7, and a gap 9b is formed between each of the adjoining drilling blades 9a and 9a so that excavated soil can be moved therethrough.