An axial-flow fan with double impellers comprising: a housing having an air channel therein, the air channel having a suction opening portion on one of axial-end sides thereof and a discharge opening portion on the other axial-end side thereof; a first impeller having a plurality of front blades and being adapted to rotate in the suction opening portion; a first motor to rotate the first impeller about an axis of the fan in one of two rotating directions; a second impeller having a plurality of rear blades and being adapted to rotate in the discharge opening portion; a second motor to rotate the second impeller about the axis in the other rotating direction opposite to the one direction; and a plurality of stationary blades radially extending and arranged stationary in the housing between the first impeller and the second impeller, characterized in that: the number of the front blades is five, the number of the stationary blades is three, and the number of the rear blades is four; the front blades are curved in a transverse cross section of the front blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the one direction; the rear blades are curved in a transverse cross section of the rear blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the other direction; the stationary blades are curved in a transverse cross section of the stationary blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the other direction and toward a direction in which the rear blades are positioned; and a rotating speed of the second impeller is slower than that of the first impeller. a housing having an air channel therein, the air channel having a suction opening portion on one of axial-end sides thereof and a discharge opening portion on the other axial-end side thereof; a first impeller having a plurality of front blades and being adapted to rotate in the suction opening portion; a first motor to rotate the first impeller about an axis of the fan in one of two rotating directions; a second impeller having a plurality of rear blades and being adapted to rotate in the discharge opening portion; a second motor to rotate the second impeller about the axis in the other rotating direction opposite to the one direction; and a plurality of stationary blades radially extending and arranged stationary in the housing between the first impeller and the second impeller, characterized in that: the number of the front blades is five, the number of the stationary blades is three, and the number of the rear blades is four; the front blades are curved in a transverse cross section of the front blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the one direction; the rear blades are curved in a transverse cross section of the rear blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the other direction; the stationary blades are curved in a transverse cross section of the stationary blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the other direction and toward a direction in which the rear blades are positioned; and a rotating speed of the second impeller is slower than that of the first impeller. the number of the front blades is five, the number of the stationary blades is three, and the number of the rear blades is four; the front blades are curved in a transverse cross section of the front blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the one direction; the rear blades are curved in a transverse cross section of the rear blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the other direction; the stationary blades are curved in a transverse cross section of the stationary blades as taken along a direction parallel to the axis so that concave portions thereof are open toward the other direction and toward a direction in which the rear blades are positioned; and a rotating speed of the second impeller is slower than that of the first impeller.