A semiconductor device includes a first electrode on a substrate, a selection device pattern, a variable resistance layer pattern, a first protective layer pattern, a second protective layer pattern and a second electrode. The selection device pattern is wider, in a given direction, than the variable resistance layer pattern. The first protective layer pattern is formed on a first pair of opposite sides of the variable resistance layer pattern. The second protective layer pattern is formed on a second pair of opposite of the variable resistance layer pattern. The second electrode is disposed on the variable resistance layer pattern.