Provided is a device for detecting thickness of a brake pad, comprising a support body, a conducting wire or a resistor body, further comprising a conducting wire provided outside the support body, and possibly further comprising a resistor, some or all of the conducting wire, resistor body, and resistor are connected to form a circuit in a certain structure, and the conducting wire or the resistor body on the support body is rubbed together with the brake pad within a certain thickness range of the brake pad. By the present invention, the range of the thickness dimension of the brake pad can be determined, or the thickness dimension of the brake pad can be continuously reflected within a certain range.