Analysis using human cells has been widely used in place of animal experiments. To obtain culture envi- ronments closer to those with in vivo, perfusion cul- ture using microfluidic devices is being studied instead of stationary culture such as in a culture dish. With conventional perfusion culture with microfluidic de- vices, pumping system is externally provided, caus- ing a large dead volume of culture medium. As a re- sult, applied drugs as well as metabolites and signal transmitters from cells are diluted. We minimized this dead volume by embedding micropumps within the device to realize a high concentration of metabolites and signal transmitters from cells by perfusion with small amounts of culture medium and its effects on the cells. Using Hep-G2, established from a human hepatoma, we successfully formed Hep-G2 spheroids which are not observed in conventional culture. Eval- uating activity from the DNA amount and albumin produced, we found that Hep-G2 spheroids formed in our device showed higher activity than conventional 2- dimensional culture. We demonstrated that the func- tionally highly integrated on-chip perfusion cell cul- ture microdevice provided cells with a culture environ- ment close to that in vivo and promoted morphological change and expression of high activity in cells.