Rotary encoder

A rotary encoder comprising:

• an axis holding unit that holds a rotary axis member;
• a rotary slit plate that is connected to the rotary axis member and rotates around a rotary axis of the rotary axis member;
• a fixed slit plate that is arranged so as to face the rotary slit plate;
• a light emitting unit that emits light to the fixed slit plate and the rotary slit plate;
• a light receiving unit that receives the light emitted from the light emitting unit;
• and
• a fixed slit table that has a first positioning unit that is attached with the fixed slit plate and positions the fixed slit plate, and a light emitting unit holding unit that holds the light emitting unit,
• the first positioning unit having
• an abutting unit to which a first side surface of the fixed slit plate abuts and that substantially does not deform, and
• a deformation unit that is arranged so as to face the abutting unit, has a tip being formed with a sharp end in a direction facing the abutting unit, and deforms by abutting a second side surface of the fixed slit plate, wherein
• the fixed slit plate is arranged in between the abutting unit and the deformation unit in a state where the fixed slit plate abuts to the abutting unit, by the deformation unit that has deformed.