A rotary type television tuner includes a chassis and a channel changing shaft extending through the chassis and having an operating knob mounted on the front end thereof for rotating the shaft. The channel changing shaft is made of a synthetic resin reinforced with glass fiber and is circular in cross-section over the greater part, the knob mounting section being formed with a flat portion and having a cross-section that is nearly semicircular. The root of the flat portion of the knob mounting section is rounded. A reinforcing rod assembly comprising a reinforcing rod made of a metal and a reinforcing rod made of a rigid synthetic resin which are connected together as by threads is embedded in the channel changing shaft including its knob mounting section. The length of the reinforcing rod of metal is such that when it is assembled as the tuner, it extends from the front end nearly to the chassis plate.