To provide a pneumatic tire for irregular terrain travel capable of enhancing the traction property on a soft road surface and the steering stability during the irregular terrain travel without impairing the traction property on a hard road surface.

In a block B provided on a tread part 2, n (n≥1) pairs of small grooves 10 extending in the circumferential direction are formed in an axial block wall Wj in the direction opposite to the tire axial direction. In the small grooves 10, the groove sectional shape orthogonal to their longitudinal direction is substantially U-shaped with a groove bottom being an arc-shaped part 11. In addition, the angle θ with respect to a tread Bs at the groove center of the small grooves 10 is set to be ≤30°.