Lactic acid-producing bacterium Lactobacillus delbrueckil subsp. delbrueckil KCTC-1047 was applied to decalcify red crab shells with variable particle sizes (A:12.7~5.0 mm, B:5.0~1.68 mm, C:1.68~0.84 mm, and D:0.84~0.25 mm). At day 5, cell ?? ?? ?? ?? growth in particle size D showed the highest value of 11.4 log cfu/ml, and pH in particle size D was the lowest value of 4.1. The residual dry weight in the culture broth was the lowest in particle size C. During the fermentation, total titratable acidity of particle size D was increased to 19.4% at day 5. Demineralization rate of crab shell in D, A, B, and C particle size was 66.37%, 64.37%, 62.02%, and 61.86%, respectively, at day 5 after fermentation of the lactic acid bacteria. Residual glucose concentration in the culture broth of particle size A was the lowest value of 1.08%. All together, these results indicate that the effect of particle size on the demineralization of crab shells by the lactic acid-producing bacteria is limited.