A turbo fan comprises: a hub coupled to a rotational shaft of a driving device; a plurality of blades installed on an outer circumference of the hub in a radial direction; and a shroud connected to the plurality of blades on opposite side of the hub centering around the blades; wherein a leading edge of the blade comprises: a connection part which is connected to the shroud; an extension part which is extended as a straight line parallelly with the rotational shaft from the hub; and a curved surface part which is formed as a convex curved surface between the extension part and the connection part.