For enlarging the application range of samples capable of being treated, decreasing the amount of samples used, preventing deterioration of samples by a change with the passage of time and preventing mixing of samples by diffusion, a micro fluidics system according to the present invention comprises a sample server which stores plural samples and which has sample efflux portions, a microchip for feeding samples to a treating portion through plural sample introducing portions communicating with the sample efflux portions and further through a microchannel, allowing the samples to be subjected to a predetermined treatment, and a sample feeder for feeding the samples stored in the sample server to the sample introducing portions through the sample efflux portions. The sample feeder comprises valves for opening and closing communication paths between the sample efflux portions of the sample server and the sample introducing portions of the microchip and pressurizing devices for pressurizing the samples stored in the sample server and pushing them out into the sample introducing portions in an open condition of the valves.