PURPOSE: To preserve a bivalve such as Ruditapes philipplinarum Adams et Reeve or Meretrix lusoria Roding for a long period without deteriorating the flavor by lining up and arranging each bivalve in a bag, vacuum-packing the bivalve and heating the bivalve while pressing the bag in a specific direction.

CONSTITUTION: The method for preserving a bivalve is to line up and arrange each bivalve in a bag 11, vacuum-pack the bag 11, place a pallet containing cage bodies 1, having a dropping lid 2 set thereon and superposed in several stages in a boiling tank 20 with conveying equipment 23 while pressing the bag 11 in the direction to close the bivalve in the bag 11, heat the bivalve at 80-100°C under atmospheric pressure for several min to tens of min, then place the bivalve in a cooling tank 21 and cool the bivalve.