To provide a tire anti-skid device which is applicable to various kinds of tires by increasing/decreasing the inner width of an anti-skid body.

An anti-skid body has a structure of a U-shaped section to be fitted to a tire, and comprises a cross part across a ground contact surface of the tire, an inner side part along an inner side surface of the tire, and an outer side part along an outer side surface of the tire. In an anti-skid device, several anti-skid bodies are fitted to the tire from its outer circumferential side, and arrayed in the entire circumference of the tire substantially at an equal spacing, and the outer side part of the anti-skid body is connected to the outer side part of the adjacent anti-skid body. In the anti-skid body 1, outer abutting members 16, 18 abutted on the outer side surface of the tire are provided on its outer side part, and inner abutting members 17, 19 abutted on the inner side surface of the tire are provided on its inner side part. The position in the width direction of the anti-skid body of each or either abutting member on the outer and inner sides is adjustable so that the distance in the width direction of the anti-skid body and the inner width W between the outer abutting member and the inner abutting member can be increased/decreased.