Wear amount detection device for automobile tires

Provided is a wear amount detection device having no special sensor provided therein, suppressing cost increase, and being capable of detecting tire wear during travel. The wear amount detection device has: a rotation sensor (2) that detects rotation of a wheel (1) so as to measure vehicle speed; a signal processing unit (3) that extracts the fluctuation in rotation speed synchronized to rotation, from rotation signals detected by this rotation sensor, and obtains a rotation speed fluctuation pattern synchronized to the rotation, from the fluctuation in rotation speed across a plurality of rotations; and a wear state determination unit (4) that finds from this obtained rotation speed fluctuation pattern a value that changes in accordance with the wear state of a tire (1a), and estimates and outputs the wear state of the tire (1) on the basis of the found value, said value being a component evoked by characteristics provided in the wheel (1) tire (1a).