A multi-flute ball end mill, comprising: a shank portion configured to rotate about a rotational axis (Ax); a cutting edge portion having a ball cutting edge portion at a tip thereof; three or more ball edges (5a, 5b, 5c) formed on the ball cutting edge portion of the cutting edge portion; three or more gashes (4a, 4b, 4c) formed between the respective ball edges (5a, 5b, 5c); three or more peripheral cutting edges (12a, 12b, 12c) continuous with end portions of the ball edges (5a, 5b, 5c) on the shank portion side; and three or more flutes (20a, 20b, 20c) formed between the respective peripheral cutting edges (12a, 12b, 12c) continuously with the respective gashes (4a, 4b, 4c), characterised in that a degree of curvature of each of the ball edges (5a, 5b, 5c) is 35% to 55%, the degree being a ratio of a length of a perpendicular line (U1-U2) drawn from an apex of a convex curved line of each of the ball edges (5a, 5b, 5c) to a line segment (O-T) connecting a rotation center point that is an intersection point between the rotational axis (Ax) and the cutting edge portion with a terminal point of each of the ball edges (5a, 5b, 5c) on the shank portion side with respect to a length of the line segment (O-T) in a front view, wherein each of the gashes (4a, 4b, 4c) includes four faces, namely a rake face (15a, 15b, 15c) of one of the ball edges (5a, 5b, 5c), a gash wall face (10a, 10b, 10c), a first gash face (8a, 8b, 8c), and a second gash face (9a, 9b, 9c), the four faces being continuous in a rotational direction of the multi-flute ball end mill, and wherein the second gash face (9a, 9b, 9c) is formed such that the closer the second gash face (9a, 9b, 9c) is to the rotation center point, the more inwardly the second gash face (9a, 9b, 9c) enters a second face (6a, 6b, 6c) of each of the ball edges (5a, 5b, 5c) continuous with a back side of each of the ball edges (5a, 5b, 5c) in the rotational direction. a shank portion configured to rotate about a rotational axis (Ax); a cutting edge portion having a ball cutting edge portion at a tip thereof; three or more ball edges (5a, 5b, 5c) formed on the ball cutting edge portion of the cutting edge portion; three or more gashes (4a, 4b, 4c) formed between the respective ball edges (5a, 5b, 5c); three or more peripheral cutting edges (12a, 12b, 12c) continuous with end portions of the ball edges (5a, 5b, 5c) on the shank portion side; and three or more flutes (20a, 20b, 20c) formed between the respective peripheral cutting edges (12a, 12b, 12c) continuously with the respective gashes (4a, 4b, 4c), characterised in that a degree of curvature of each of the ball edges (5a, 5b, 5c) is 35% to 55%, the degree being a ratio of a length of a perpendicular line (U1-U2) drawn from an apex of a convex curved line of each of the ball edges (5a, 5b, 5c) to a line segment (O-T) connecting a rotation center point that is an intersection point between the rotational axis (Ax) and the cutting edge portion with a terminal point of each of the ball edges (5a, 5b, 5c) on the shank portion side with respect to a length of the line segment (O-T) in a front view, wherein each of the gashes (4a, 4b, 4c) includes four faces, namely a rake face (15a, 15b, 15c) of one of the ball edges (5a, 5b, 5c), a gash wall face (10a, 10b, 10c), a first gash face (8a, 8b, 8c), and a second gash face (9a, 9b, 9c), the four faces being continuous in a rotational direction of the multi-flute ball end mill, and wherein the second gash face (9a, 9b, 9c) is formed such that the closer the second gash face (9a, 9b, 9c) is to the rotation center point, the more inwardly the second gash face (9a, 9b, 9c) enters a second face (6a, 6b, 6c) of each of the ball edges (5a, 5b, 5c) continuous with a back side of each of the ball edges (5a, 5b, 5c) in the rotational direction.