In this report, the author presents the experimental results of the relation betneen the dredging capacity of model grab-buckets and the character of sand and gravel. In order to investigate the smilitude on the dredging capacity of grab-bucket, the model grab-buckets with the capacity of 0.005m3 were those of larger models with the capapcity of 0.05m3 which had been reported in the first report of this series. It was fond tat both the experiments with small and large model grab-buckets support the same relation between the weight of grabbedd soil Ws and the dimensions of buckets, i.e.
　Ws/Wg=KL√(B/2Wg)-C
　with the linear coeffcient K being determined by soi l condition and type of grab-bucket.