An end mill comprising: an end mill body formed of a shank portion and a cutting edge portion having a rotation center axis (O); three or more end cutting edges located at a front end side of the end mill body ; peripheral cutting edges located at a rear side of the respective end cutting edges ; chip discharging flutes located between corresponding two of the peripheral cutting edges ; heels located at respective opposite sides of the peripheral cutting edges to interpose a corresponding one of the chip discharging flutes therebetween; and flat surface shaped rake surfaces located between the end cutting edges and the chip discharging flutes ; wherein a cross sectional shape of each of the chip discharging flutes located between corresponding two of the peripheral cutting edges comprises a first concave curve located on a side of a corresponding one of the peripheral cutting edges , a second concave curve located on a side of a corresponding one of the heels , and a protrusion located between the first concave curve and the second concave curve ; at least part of each side of the protrusion is part of the first concave curve and the second concave curve , respectively; the first concave curved surface , the second concave surface , and the protrusion of a respective chip discharging flute extend in a spiral manner from the termination of a corresponding rake surface to the termination of the cutting edge portion ; and a ratio (h/H) of a distance h from a circle c comprising a maximum diameter (d) capable of being drawn in the end mill body centered on the rotation center axis (O) to a top of the protrusion to a distance H from the circle c to the peripheral cutting edge is 0.1 to 0.4 times. an end mill body formed of a shank portion and a cutting edge portion having a rotation center axis (O); three or more end cutting edges located at a front end side of the end mill body ; peripheral cutting edges located at a rear side of the respective end cutting edges ; chip discharging flutes located between corresponding two of the peripheral cutting edges ; heels located at respective opposite sides of the peripheral cutting edges to interpose a corresponding one of the chip discharging flutes therebetween; and flat surface shaped rake surfaces located between the end cutting edges and the chip discharging flutes ; wherein a cross sectional shape of each of the chip discharging flutes located between corresponding two of the peripheral cutting edges comprises a first concave curve located on a side of a corresponding one of the peripheral cutting edges , a second concave curve located on a side of a corresponding one of the heels , and a protrusion located between the first concave curve and the second concave curve ; at least part of each side of the protrusion is part of the first concave curve and the second concave curve , respectively; the first concave curved surface , the second concave surface , and the protrusion of a respective chip discharging flute extend in a spiral manner from the termination of a corresponding rake surface to the termination of the cutting edge portion ; and a ratio (h/H) of a distance h from a circle c comprising a maximum diameter (d) capable of being drawn in the end mill body centered on the rotation center axis (O) to a top of the protrusion to a distance H from the circle c to the peripheral cutting edge is 0.1 to 0.4 times. <EOS>