Magnetic encoder and roller bearing unit having magnetic encoder

A magnetic encoder comprising:

• a magnet portion formed by circularly arranging a magnetic material comprising a magnetic powder and a binder for the magnetic powder, wherein
• the binder comprises at least a thermoplastic resin and an impact resistance-improving agent, and
• a bending deflection amount of the magnetic portion falls within a range of 2 to 15 mm in an experimental condition that a thickness of magnetic material is 3.0 mm, span distance is 50 mm and temperature is 23° C. under ASTM D790, wherein
• the thermoplastic resin is a polyamide 12 resin, and
• the impact resistance-improving agent is a modified polyamide 12 resin which is a block copolymer comprising:
• a hard segment of the polyamide 12;
• and
• a soft segment of at least one of a polyester component and a polyether component.