A micro channel element includes a semiconductor substrate and a channel. The micro channel element is produced as follows. A mask having an opening with a desired pattern is formed on a surface of the semiconductor substrate. The semiconductor substrate on which the mask is formed is dipped in a solution of hydrofluoric acid or a solution mixture of hydrofluoric acid and ethyl alcohol. A cathode is arranged near the surface of the substrate dipped in the solution. An anode is connected to the other surface of the semiconductor substrate. A porosity is imparted to a portion of the surface of the semiconductor substrate which corresponds to the opening of the mask by applying a voltage across the cathode and anode. A high-temperature treatment is performed for the semiconductor substrate removed from the solution to increase the pore size and extend the branches of pores of the porous portion on the surface of the semiconductor substrate, thereby forming the micro channel.