The utility model discloses an insulation detector which comprises an insulation detector body. The insulation detector body comprises two detecting ports which are respectively connected with a detecting line through a detecting joint that is arranged on an insulating handle. The detecting line is spirally arranged in the insulating handle. The other end of each of the two detecting lines is connected with a metal sheet which is used for contacting with a surface to be detected. The distance between the two metal sheets is adjustable, and furthermore the length of the insulating handle is adjustable. In the insulation detector provided by the utility model, the distance between the metal sheets which contact with the surface to be detected is adjustable, and high convenience is realized. Under a precondition that the position of one metal sheet is fixed, the position of the other metal sheet can be adjusted, and high reliability of detecting data at a same position is realized. Additionally, the length of the insulating handle is adjustable, and using is facilitated at the position which is relatively far from the insulation detector body, thereby improving applicability of the insulation detector provided by the utility model.