A method of preparing a liver tissue structure, comprising: preparing a cultured form by co-culturing a hepatic endoderm cell derived from a human induced pluripotent stem cell and a human vascular endothelial cell and a human mesenchymal stem cell; performing an assay of a plurality of functions of the cultured form by using a Pearson product-moment correlation coefficient; and picking, as a tissue structure, a cultured form in which a value obtained by the assay is closer to a value of a cell or biological tissue sampled from an adult than a value of a cell or biological tissue sampled from a fetus, wherein the co-culturing is performed using a microchamber having an equivalent diameter in a range from 20 μm to 2.5 mm and a depth in a range from 20 μm to 1000 μm and using a culture chamber having a culture surface which is a cell non-adhesive surface, the hepatic endoderm cell: the human vascular endothelial cell: and the human mesenchymal stem cell are co-cultured at a ratio of 10:5-10:1-2, and the cells are seeded at a density of 20 to 2000 cells per microchamber, the microchamber is formed of a bottom portion and an opening, the opening is defined by a wall that surrounds an area from a boundary between the opening and the bottom portion to an end of the opening, the wall having a taper angle in a range from 1 to 20 degrees, the bottom portion has one of a hemispherical shape and a truncated cone shape, and the plurality of functions are expression levels of genes including VKORC1, UBD, TNFSF10, TDO2, TAP1, SORD, SERPING1, PXMP2, PSMB9, PSMB8, PNPLA7, PLG, ORM2, ORM1, NFIC, MX1, MGLL, MAT1A, LRG1, KNG1, KLF9, ITIH4, ILI3RA1, IGFBP4, IFIT1, HSD3B7, HRG, HP, HGD, HAMP, G0S2, FGGY, FBP1, F12, ETFDH, DEFB1, CTSO, CLDN2, CFI, CFH, CFB, C3, APOC3, ANG, ALDOB, ALDH3A2, ACAT1, ABCC3 and ABCA6. preparing a cultured form by co-culturing a hepatic endoderm cell derived from a human induced pluripotent stem cell and a human vascular endothelial cell and a human mesenchymal stem cell; performing an assay of a plurality of functions of the cultured form by using a Pearson product-moment correlation coefficient; and picking, as a tissue structure, a cultured form in which a value obtained by the assay is closer to a value of a cell or biological tissue sampled from an adult than a value of a cell or biological tissue sampled from a fetus, wherein the co-culturing is performed using a microchamber having an equivalent diameter in a range from 20 μm to 2.5 mm and a depth in a range from 20 μm to 1000 μm and using a culture chamber having a culture surface which is a cell non-adhesive surface, the hepatic endoderm cell: the human vascular endothelial cell: and the human mesenchymal stem cell are co-cultured at a ratio of 10:5-10:1-2, and the cells are seeded at a density of 20 to 2000 cells per microchamber, the microchamber is formed of a bottom portion and an opening, the opening is defined by a wall that surrounds an area from a boundary between the opening and the bottom portion to an end of the opening, the wall having a taper angle in a range from 1 to 20 degrees, the bottom portion has one of a hemispherical shape and a truncated cone shape, and the plurality of functions are expression levels of genes including VKORC1, UBD, TNFSF10, TDO2, TAP1, SORD, SERPING1, PXMP2, PSMB9, PSMB8, PNPLA7, PLG, ORM2, ORM1, NFIC, MX1, MGLL, MAT1A, LRG1, KNG1, KLF9, ITIH4, ILI3RA1, IGFBP4, IFIT1, HSD3B7, HRG, HP, HGD, HAMP, G0S2, FGGY, FBP1, F12, ETFDH, DEFB1, CTSO, CLDN2, CFI, CFH, CFB, C3, APOC3, ANG, ALDOB, ALDH3A2, ACAT1, ABCC3 and ABCA6.