This study is the first step towards the proper application of microcirculatory blood flow in the human cardiovascular system. Blood plays an indispensable role in mass and gas transfer in the capillaries ; thus, it is important to make clear the behavior of human blood in capillary vessels of 5-8 μm in diameter. In order to clarify the blood flow behavior in capillaries, a new micro capillary vascular network model allowing the clear observation of flows using a high-powered microscope was developed inside a silica glass using a femto-second laser micro/nano fabrication system. Using this system it was possible to fabricate three-dimensional micro-tubes and micro-cavities inside a transparent material. The present capillary models have a diameter of about 5-20 μm. We succeeded in observing blood flow in this capillary model using a micro-flow visualization technique. Red blood cells and tracer particles sometimes flowed smoothly in the model, but sometimes adhered to the channel wall and formed capillary blockage. This phenomenon occurred independently of particle type and particle diameter. The surface roughness on the channel wall seemed to be involved in these particle-adhering phenomena.