In preparing a high-concentrated soluble thrombomodulin-containing solution having a concentration of 10 mg/mL or above, foam-inhibiting effect can be attained by any means selected from among (a) allowing the presence of a nonionic surfactant, benzyl alcohol or chlorobutanol, (b) an inner wall of the container to be used in dissolving the soluble thrombomodulin-containing freeze-dried preparation is coated with silicone, and (c) a pressure in the container to be used in dissolving the soluble thrombomodulin-containing freeze-dried preparation is kept at a reduced pressure. <；??>；Further, a soluble thrombomodulin freeze-dried preparation excellent in stability is also provided which can be dissolved in 0.1 mL to 2 mL of aqueous solution for dissolution to prepare a high-concentrated soluble thrombomodulin-containing solution having a concentration of 10 mg/mL or above and exhibiting an osmotic pressure ratio of 0.5 to 2.0 at the time of resolution.
