An impeller comprising: a hub having an annular shape; and a plurality of blades radially arranged along an outer peripheral surface of the hub, the impeller being configured in such a manner that a fluid having flowed from a leading edge side of the blade along a rotation axis is discharged from a trailing edge side of the blade outward in the radial direction intersecting the rotation axis, wherein a pressure surface of the blade includes: a first pressure surface extending from the hub side at an angle of 90 degrees or less with respect to the forward direction of the direction of rotation of the impeller; a second pressure surface extending from the first pressure surface at an angle of more than 90 degrees with respect to the forward direction of the direction of rotation of the impeller; and a third pressure surface extending from the second pressure surface at an angle of 90 degrees or less with respect to the forward direction of the direction of rotation of the impeller, and the pressure surface of the blade has a curved shape bending forward in the rotation direction on an inner peripheral side, while having an S-shape formed of the first pressure surface, the second pressure surface, and the third pressure surface on the outer peripheral side. a hub having an annular shape; and a plurality of blades radially arranged along an outer peripheral surface of the hub, the impeller being configured in such a manner that a fluid having flowed from a leading edge side of the blade along a rotation axis is discharged from a trailing edge side of the blade outward in the radial direction intersecting the rotation axis, wherein a pressure surface of the blade includes: a first pressure surface extending from the hub side at an angle of 90 degrees or less with respect to the forward direction of the direction of rotation of the impeller; a second pressure surface extending from the first pressure surface at an angle of more than 90 degrees with respect to the forward direction of the direction of rotation of the impeller; and a third pressure surface extending from the second pressure surface at an angle of 90 degrees or less with respect to the forward direction of the direction of rotation of the impeller, and the pressure surface of the blade has a curved shape bending forward in the rotation direction on an inner peripheral side, while having an S-shape formed of the first pressure surface, the second pressure surface, and the third pressure surface on the outer peripheral side. a first pressure surface extending from the hub side at an angle of 90 degrees or less with respect to the forward direction of the direction of rotation of the impeller; a second pressure surface extending from the first pressure surface at an angle of more than 90 degrees with respect to the forward direction of the direction of rotation of the impeller; and a third pressure surface extending from the second pressure surface at an angle of 90 degrees or less with respect to the forward direction of the direction of rotation of the impeller, and the pressure surface of the blade has a curved shape bending forward in the rotation direction on an inner peripheral side, while having an S-shape formed of the first pressure surface, the second pressure surface, and the third pressure surface on the outer peripheral side.