PROBLEM TO BE SOLVED: To provide a Ni-Fe based permalloy alloy having excellent hot workability and AC magnetic properties.SOLUTION: Provided is a Ni-Fe based permalloy alloy having a componential composition comprising, by mass, 0.001 to 0.03% C, 0.01 to 0.5% Si, 0.1 to 1.6% Mn, 0.03% or lower of P, 0.0020% or lower of S, 74 to 80% Ni, 0.3% or lower of Cr, 3 to 5% Mo, 2 to 6% Cu, 0.001 to 0.03% Al, 0.01 to 0.10% Ti, 0.004% or lower of N, 0.001 to 0.004% B and 0.005% or lower of O, and the balance Fe with inevitable impurities. Preferably, the N and Ti are comprised so as to satisfy 571.4×N-42.86×Ti≤1, and further preferably, the content of B after magnetic annealing is 0.0004 mass% or lower.
