A composite of metal and resin and a manufacturing method require a metal piece and a resin piece, and the surface of the metal piece is etched to include a number of micropores. Each micropore includes a first inclined hole and a second inclined hole, the first inclined hole and the second inclined hole diverging from each other below the surface of the metal piece. The first inclined hole and the second inclined hole extend downwards from a common starting hole which is symmetric around an axis perpendicular to the surface of the metal piece. The resin is embedded in the micropores to combine with the metal piece, where the bonding strength of the composite of metal and resin is increased.