A Ni—Ti-based alloy material includes a matrix phase consisting essentially of a Ni—Ti-based alloy and having a B2 type crystal structure. A nonmetallic inclusion is present in the matrix phase, in which 99% by mass or more of the nonmetallic inclusion is a TiC-based inclusion having a NaCl type crystal structure, the TiC-based inclusion has a lattice misfit (δ) in a range of 0.4238 or more and 0.4259 or less. The lattice misfit (δ) is represented by Expression δ=(a1−a2)/a2, where a1 is a lattice constant (Å) of the TiC-based inclusion and a2 is a lattice constant (Å) of the matrix phase.