There is provided a lead frame which comprises: a lead frame body comprising a sheet-shaped body made of metal; a groove portion for forming a lead which is formed by a predetermined depth in a lead forming region on a surface of the lead frame body; and a lead portion formed so that the lead portion can protrude from the groove portion onto the surface of the lead frame body, the lead portion being made of material different from material of the lead frame body. A thin type semiconductor device is provided in which the above lead frame is used and after a chip is mounted, the lead frame body is removed by means of etching.