This disclosure is to provide an elastic crawler drive mechanism including an elastic crawler (20) with engaging portions (22) disposed on an endless belt (21), and a sprocket (10) having teeth (12), wherein: engaging surfaces (F2) of the engaging portions (22) have flat engaging planes (22b) in contact with a part of tooth surfaces (F1) of the sprocket (10) when in contact with tooth bottom surfaces (11a) of the sprocket (10), and when the engaging portions (22) are in contact with the tooth bottom surfaces (11a), and simultaneously the engaging planes (22b) are in contact with the tooth surfaces (F1) of the sprocket (10), at least one of the tooth surfaces (F1) of the sprocket (10) and the engaging planes (22b) of the engaging portions (22) form gaps (C) between the tooth surfaces (F1) and the engaging planes (22b), on sides closer to the tooth bottom surfaces (11a) than contact portions (P) of the tooth surfaces (F1) and the engaging planes (22b).