A fan includes a fan frame and a fan wheel. The fan frame includes a frame body and a first waved structure. The frame body has a wind enter side and a wind exhaust side, wherein the wind enter side is opposite to the wind exhaust side. The first waved structure is formed on the wind enter side of the frame body. The first waved structure has a plurality of first peaks and a plurality of first valleys, wherein the first peaks and the first valleys are arranged separately. The fan wheel is rotatably disposed in the fan frame.