To provide a detection device and a detection method capable of efficiently and correctly detecting the deformation states of tires in a traveling with a simple structure.

A detection device 1 for detecting the deformation states of tires 6 in a traveling vehicle 5 includes imaging means 2, storage means 3, and determination means 4. The imaging means is mounted on the traveling vehicle 5 and captures images of predetermined patterns 7 arranged on a road surface 8 in a detection area P. The storage means 3 stores the images of the predetermined patterns 7 previously captured by the imaging means 2 in the detection area P before the deformation of the tires 6 as reference images. The determination means 4 compares the images captured in the detection area P with the reference images stored in the storage means 3, and determines the deformation states of the tires 6 on the basis of the changes of the predetermined patterns 7 between the two kinds of images.