formed on a side surface of a first substrate a second substrate faces to the side surface of the first substrate a third substrate is arranged so that the first and second substrates contact each other closely a micro flow path and a micro chamber are formed between the first and second substrates the micro flow path and the micro chamber communicate with each other and including an inlet and outlet respectively a fifth substrate contains the first second and third substrates a fourth substrate fits in the fifth substrate the first and second substrates are pressed against each other by thread fastening for the fourth and fifth substrates application_number US 43982106 A description hereafter an embodiment of micro fluidic device of the invention will be described with making reference to the drawings fig1 is an oblique projection exploded view of a micro fluidic device 100 and fig2 includes an upper view fig2 a and a longitudinally cross sectional view fig2 b of a parallel treating areas of the micro fluidic device 100 incidentally fig2 b does not include section line for three substrates 102 104 between two substrates 101 and 105 in the micro fluidic device 100 as the embodiment two kinds of liquid.