An EUV mask according to an embodiment includes a substrate, a first line-shaped portion provided on the substrate, a second line-shaped portion provided on the substrate, a first sidewall disposed on a side surface of the first line-shaped portion, and a second sidewall disposed on a side surface of the second line-shaped portion. A first layer and a second layer are stacked in the first and second line-shaped portions. The first layer includes a first material. The second layer includes a second material. The first and second sidewalls include an oxide of the first material and cover a side surface of the first layer and a side surface of the second layer.