To provide an ice/snow accretion preventive material which positively prevents ice/snow accretion on an angle steel member of a steel tower, facilitates work such as dimensional adjustment in the construction field, is applicable to a structure inclusive of a joint portion, etc., facilitates mounting thereof in the angle steel member, does not mar the appearance, and is excellent in durability.

The ice/snow accretion preventive material 1 is made of a synthetic resin foam molded body having a cross section almost conforming to an inner space 53 of the angle steel member 50 forming the steel tower. The ice/snow accretion preventive material is fitted into the inner space 53 of the angle steel 50 so as to fill the space 53, and then fixed to the space 53 by engaging members 2.