To accurately estimate the tire grip of a wheel, regardless of smooth road running state or rough road running state.

A device for estimating tire grip of a wheel comprises the steps of: calculating a first vertical load Fz1i of each wheel, based on load transfer in longitudinal and lateral directions of a vehicle (S20); calculating a second vertical load Fz2i of each wheel, based on the deformed amounts of suspension members caused by bounds and rebounds of wheels (S30), setting the vertical load Fzi of each wheel as the first vertical loads Fz1i (S80-100, and 190) when running on the non-rough road (S40), setting the vertical load Fzi of each wheel as the second vertical loads Fz2i (S50-70, and 190) when running on the rough road (S40), and calculating tire grip fl and fr of the right and left front wheels, by using a self-aligning torque model value Tsato calculated on the basis of the vertical Fzi (S200).