A substrate for a magnetic read/write head is disclosed. The substrate can reduce detachment of crystal grains when unexpected vibrations or impacts are applied. The substrate may be machined when the substrate is cut into strips or a flow path surface recess is formed to produce the magnetic read/write head. The reduced detachment of crystal grains makes the magnetic read/write head more resilient to chipping, which allows the magnetic read/write head to have good performance in read/write.