An air blower, comprising: a casing (7, 607) having an air inlet portion and an air outlet portion; a fan provided in the casing (7, 607) so as to be rotatable; and a fan guard (11, 411, 611) provided at the air outlet portion of the casing (7, 607), wherein: the fan comprises a boss portion, and a plurality of blades provided on an outer circumferential surface of the boss portion; the fan guard (11, 411, 611) comprises a guide portion (31, 131, 231, 331, 531) having a tubular outer shape, which protrudes toward the fan; a center in a distal end shape (43, 143, 243), which is defined by a contour line (41, 141, 241) of a distal end portion of the guide portion (31, 131, 231, 331, 531), matches with a rotation axis of the boss portion; and a center in a root shape (53, 153, 253), which is defined by a contour line (51, 151, 251) of a root portion of the guide portion (31, 131, 231, 331, 531), is shifted with respect to the rotation axis of the boss portion, characterized in that: on an inlet side of the fan, airflow resistance is larger on one radial side than on another radial side across the rotation axis of the boss portion; and a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the one side on which the airflow resistance is relatively large is larger than a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the another side on which the airflow resistance is relatively small. a casing (7, 607) having an air inlet portion and an air outlet portion; a fan provided in the casing (7, 607) so as to be rotatable; and a fan guard (11, 411, 611) provided at the air outlet portion of the casing (7, 607), wherein: the fan comprises a boss portion, and a plurality of blades provided on an outer circumferential surface of the boss portion; the fan guard (11, 411, 611) comprises a guide portion (31, 131, 231, 331, 531) having a tubular outer shape, which protrudes toward the fan; a center in a distal end shape (43, 143, 243), which is defined by a contour line (41, 141, 241) of a distal end portion of the guide portion (31, 131, 231, 331, 531), matches with a rotation axis of the boss portion; and a center in a root shape (53, 153, 253), which is defined by a contour line (51, 151, 251) of a root portion of the guide portion (31, 131, 231, 331, 531), is shifted with respect to the rotation axis of the boss portion, characterized in that: on an inlet side of the fan, airflow resistance is larger on one radial side than on another radial side across the rotation axis of the boss portion; and a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the one side on which the airflow resistance is relatively large is larger than a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the another side on which the airflow resistance is relatively small. the fan comprises a boss portion, and a plurality of blades provided on an outer circumferential surface of the boss portion; the fan guard (11, 411, 611) comprises a guide portion (31, 131, 231, 331, 531) having a tubular outer shape, which protrudes toward the fan; a center in a distal end shape (43, 143, 243), which is defined by a contour line (41, 141, 241) of a distal end portion of the guide portion (31, 131, 231, 331, 531), matches with a rotation axis of the boss portion; and a center in a root shape (53, 153, 253), which is defined by a contour line (51, 151, 251) of a root portion of the guide portion (31, 131, 231, 331, 531), is shifted with respect to the rotation axis of the boss portion, characterized in that: on an inlet side of the fan, airflow resistance is larger on one radial side than on another radial side across the rotation axis of the boss portion; and a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the one side on which the airflow resistance is relatively large is larger than a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the another side on which the airflow resistance is relatively small. on an inlet side of the fan, airflow resistance is larger on one radial side than on another radial side across the rotation axis of the boss portion; and a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the one side on which the airflow resistance is relatively large is larger than a distance between the contour line (51, 151, 251) of the root portion of the guide portion (31, 131, 231, 331, 531) and the rotation axis of the boss portion on the another side on which the airflow resistance is relatively small.