PROBLEM TO BE SOLVED: To provide a liquid for organism intravascular blood substitution having a blood exclusion ability and a sustainability more sufficient than a blood substitution liquid conventionally used, and having the blood exclusion ability having substantially no toxicity, and to provide a prefilled syringe filled with it.SOLUTION: In an organism intravascular inspection, a liquid for organism intravascular blood substitution 1 is injected into a blood vessel in order to substitute the blood of the site to be examined in an organism blood vessel. And the liquid for blood substitution 1 is a transparency aqueous liquid consisting of an aqueous medium harmless to organisms, and a hydrophilic high polymer added to the aqueous medium to increase a viscosity.
