Changes in available lysine and water soluble proteins were checked to obtain the desirable condition of processing for boiled Neverita didyma under the various autoclaving temperatures and times. It was also carried out to assess the affect of heat treatments upon the solubility of coagulable substances in boiled products. In order to evaluate the nutritional quality of processed Neverita didyma under the highest available lysine retention and without bacteria, it was studied the value of pepsin-pancreatin digest residue index in comparison with unprocessed (raw) material. The crude protein content of raw material was higher than that of the other mollusks, while the content of crude fat was showing lower value. It was noticed that the higher contents of coagulable substances and water soluble proteins in processed Neverita didyma were obtained under the conditions, retort temperature at $120^{circ}C$ above, and 40-60 min. sterilization. After the pannel test, the coagulable substances were not found below the level of $0.40{pm}0.03$ gram nitrogen/ml of juice. The remarkable retention of available lysine (FDNB-reactive lysine) was resulted in the conditions of autoclaving at $115^{circ}C$ for 40 minutes in boiled Neverita didyma products, and that processing condition was coincide with the condition of commercial sterilization for boiled top shell. It was revealed that the boiled meat of Neverita didyma showed the higher PPDRI(65.85) than that of raw material (63.16).