It is an object of the present invention to effectively suppress the occurrence of burrs in machining of a fiber-reinforced composite material, etc., using an end mill. An end mill includes first cutting edges 4 which spiral in a direction defining a positive helix angle and second cutting edges 5 which spiral in a direction defining a negative helix angle, the first cutting edges 4 and the second cutting edges 5 being disposed at positions shifted in a circumferential direction. The first cutting edges 4 and the second cutting edges 5 are each configured to be continuous over an effective cutting edge length, and at a tool top, a phase angle P1 between one of the first cutting edges 4 and its adjacent second cutting edge 5 located toward the back in a tool rotation direction is set to be different from a phase angle P2 between the second cutting edge 5 and its adjacent first cutting edge 4 located toward the back in the tool rotation direction.