A rotary encoder includes a case made of insulating resin, a rotatable operation shaft, a slidable brush fixed to the operation shaft, and a signal contact embedded in a surface of the case. The slidable brush has a contacting section slidable on a surface of the case on a predetermined circumference according to a rotation of the operation shaft. The signal contact has an upper surface flush with the surface of the case, a first side surface connected to the upper surface at a first corner having a right angle, a second side surface connected to the upper surface at a second corner having a right angle, and a lower surface opposite to the upper surface. The first and side surfaces are positioned on the predetermined circumference. The lower surface has a width smaller than a width of the upper surface. This rotary encoder has a small size and outputs a signal precisely.