COMPOSITION FOR PLASMA AND SERUM SEPARATION, AND CONTAINER FOR BLOOD TESTING

The invention provides a serum or plasma separating composition which can compensate for the lack of initial thixotropy even at a reduced inorganic powder concentration and in which crevices or the like are less likely to be created in a partition wall formed of the separating composition after being centrifuged. The serum or plasma separating composition contains a liquid resin component having a partition wall-forming capability, a hydrophilic inorganic powder, a hydrophobic inorganic powder, and an organic compound serving as a thixotropy enhancer, wherein the organic compound is a polyalkylene glycol and/or a derivative thereof and is made of at least one type of polymer selected from the group consisting of: 1) a homopolymer of a single type of monomer selected from C 3 to C 5 alkylene oxide monomers; 2) a random copolymer, an altering copolymer, or a periodic copolymer of two or more types of monomers selected from C 2 to C 5 alkylene oxide monomers; 3) a block copolymer of two or more types of monomers selected from C 3 to C 5 alkylene oxide monomers; and 4) a graft copolymer of at least one type of polymer selected from the polymers 1) to 3), the polyalkylene glycol and/or the derivative thereof has a number average molecular weight of 500 to 100000, both inclusive, and the content of the polyalkylene glycol and/or the derivative thereof in the total amount of the serum or plasma separating composition is 0.2% to 5% by weight, both inclusive.