To dissolve the entrainment of the air in an underfill material filling and injection process and yet, to make it possible to display the filling speed of the an underfill material to the maximum, to provide the underfill material optimum to a semiconductor device of a flip-chip mounting system and to provide a highly reliable semiconductor element.

In an underfill material for sealing a flip chip of a constitution that the size of the gap between a chip and a substrate is 10 μm or longer to 50 μm or shorter and the size of the shortest gap between a bump and a bump is 50 μm or longer to 320 μm or shorter, the underfill material is a liquid resin composition containing a filling material, which consists of spherical particles of the largest grain diameter of 5 μm or longer to 10 μm or shorter and a specific surface area of 1.4 m2/g or longer to 3.2 m2/g or shorter. Moreover, the semiconductor device is sealed by using the liquid resin composition.