In order to develop the substitutive materials for natural baits of swimming crab pots, the attracting effects of swimming crab such as the preference of baits which were made of the by-products of marine and stock raising through the water tank experiments and fishing experiments. On the investigation of mean entrapped catch number to the pot by the baits after putting the 4 kinds of baits, mackerel(M), mackerel with grinded mackerel s internals(MMI), mackerel with tuna s internalsMMI) and makerel with grinded krill(MK) each in one pot by turns, MMI and MK were entrapped mean 3.9(13.0%) and they were a little more comparing to M, and MTI is least with mean 2.1(7.0%)(F=12.913, P 〈 0.05). Otherwise, on the preference investigation of swimming crabs by the baits after putting the 4 kinds of baits in the 4 pots each, M was entrapped mean 3.0(10%), but MMI, MTI and MK were mean 1.2(4.0%), 1.0(3.3%) and 1.5(5.0%) each and they were only 30-50% of M(F=13.398, P 〈 0.05). On the preference investigation of swimming crabs by the 5 kinds of baits, mackerel(M), and krill(K), manila clam(MC), pig s fat(PF) and chicken s head(CH) which were used in substitutive baits, M was entrapped mean 3.2(10.7%), but K was about 50% of catch of M with mean 1.6(5.3%), and MC, PF and CH were very few with mean 0.1-0.2(0.3-0.7%)(F=89.186, P 〈 0.05). On the preference investigation of swimming crabs by the pots which were put each the 3 kinds of baits, original krill(K), grinded krill with gluten and soybean oil cake(KGGS) and grinded krill with gluten, soybean oil cake and glycine(KGGSGL) in the blue fluorescent hexahedral plastic bait cages(BF), and which were put the mackerel(M) in the non-fluorescent hexahedral red plastic bait cage(RFN), it was entrapped mean 3.0(10.0%) in the pot which was put the mackerel in the RFN, and the same level in the pots which were put the K and KGGSGL in the BF, but it was mean 2.0(6.7%) in the pots which was put the KGGS in BF and it was decreased by 30% of catch comparing to RFN(F=3.750, P 〈 0.05). On the preference investigation of swimming crab by the pots which was put grinded tuna with gluten, soybean oil cake and glycine(TIGSGL) in the blue fluorescent hexahedral plastic bait cage(BF), and which was put mackerel(M) in the nonfluorescent hexahedral red plastic bait cage(RFN), it was entrapped mean 3.3(11.0%) in the pot which was put mackerel in RFN, and mean 2.7(9.0%) in the pot which was put TIGSGL in BF and it was about 15% less comparing to use bait M(t=1.387, P 〈 0.05). As a results of fishing experiments, a plan for enhancing catching efficiency of TIGSGL will be required because catching efficiency of TIGSGL, alternative bait, was half of fish catching efficiency of natural bait using mackerel. Fishing experiments were conducted 3 times using reinforced substitutive artificial bait that is reinforced attractive effect of TIGSGL and composed of tuna intestine, grinded mackerel, gluten, soybean cake, glycine and alanine(TIMGGSGLA). Catching efficiency of TIMGGSGLA was about 80% of that of natural bait made of mackerel.