A hard film whose composition formula satisfies M1-a-bCaNb, in which M is at least one element selected from Ti, Cr and Al, or is the element and at least one element selected from Group 4 elements except for Ti, Group 5 elements, Group 6 elements except for Cr, Si, Y, and rare earth elements. Atomic ratios of M, C and N satisfy: 0.01≦a≦0.50; 0.10≦b≦0.50; and 0