We designed a high-speed recording head with a core of Co-Ni-Fe film, which had a saturation-induction of 2 T for the recording to high coercivity media. The time response of the head field was calculated by using a 3D electromagnetic field simulator (JMAGWorks™). We found that a faster rise time of the head field was obtained by reducing the core length of the head to 10 μ m, even when the core consisted of the Co-Ni-Fe film,w hich had al ow resistivity of 0.2 μ Qm . The small core Co-Ni-Fe heads are suited to the high-speed and high-density recording because of their good write performance at the frequency of 250 MHz for a medium with the coercivity of 400 kA/m (5 kOe.)