A method of estimating the dynamic state amount of a tire comprising steps of: detecting contact time from a temporal waveform of a deformation amount at axisymmetrical positions on the inner side of the belt portion of a tire tread in the radial direction, the positions being equally distant in the axial direction from the center in the axial direction of the tire on almost the same cross-section in the radial direction or a temporal waveform of a differential value obtained by time differentiating the deformation amount; measuring a wheel speed; calculating indices (k A, k B) of contact length of the tire by multiplying the detected contact time by the wheel speed; calculating contact length ratio being ratio of indices (k A, k B) of contact length at the axisymmetrical positions; estimating lateral force generated on the tire from the contact length ratio; detecting time between the deformation point outside the contact patch on the leading side and the deformation point outside the contact patch on the trailing side from the temporal waveform of the deformation amount or the temporal waveform of the differential value; calculating indices of deformation length outside the contact patch by multiplying the detected time between deformation points outside the contact patch (D1 and D2) by wheel speed; calculating deformation length ratio outside contact patch being ratio of deformation length indices outside the contact patch at the axisymmetrical positions; estimating camber angle of the tire from the contact length ratio and deformation length ratio outside the contact patch; and correcting the estimated lateral force by using estimated camber angle; wherein a dynamic state amount of the tire is estimated when the lateral force acts on the running tire. detecting contact time from a temporal waveform of a deformation amount at axisymmetrical positions on the inner side of the belt portion of a tire tread in the radial direction, the positions being equally distant in the axial direction from the center in the axial direction of the tire on almost the same cross-section in the radial direction or a temporal waveform of a differential value obtained by time differentiating the deformation amount; measuring a wheel speed; calculating indices (k A, k B) of contact length of the tire by multiplying the detected contact time by the wheel speed; calculating contact length ratio being ratio of indices (k A, k B) of contact length at the axisymmetrical positions; estimating lateral force generated on the tire from the contact length ratio; detecting time between the deformation point outside the contact patch on the leading side and the deformation point outside the contact patch on the trailing side from the temporal waveform of the deformation amount or the temporal waveform of the differential value; calculating indices of deformation length outside the contact patch by multiplying the detected time between deformation points outside the contact patch (D1 and D2) by wheel speed; calculating deformation length ratio outside contact patch being ratio of deformation length indices outside the contact patch at the axisymmetrical positions; estimating camber angle of the tire from the contact length ratio and deformation length ratio outside the contact patch; and correcting the estimated lateral force by using estimated camber angle; wherein a dynamic state amount of the tire is estimated when the lateral force acts on the running tire.