PURPOSE: To contrive to reinforce a roller wheel passing surface, as well as to lighten the crawler by a constitution wherein curved protruded parts are formed.

CONSTITUTION: Core bard 3, a gutter shape dent 4 of which is fitted in the central dent of a crawler main body 1, are disposed in a row with the predetermined intervals longitudinally to the crawler main body 1 to form engaement holes 8 between the gutter shape dents, with which the tooth of a sprocket engages. According to the constitution as described above, the roller wheel passing surfaces 9 are reinforced with the curved protruded parts 6 and the lightening as well as the improvement of strength of the crawler can be achieved coupled with wing shape parts 7 being imbedded in the main body 1.