To provide mechanism that can change a radial angle and can change its radius by extending and-contracting motion.

Regarding radial angle changeable mechanism, the radial angles of other components are changed by the change of the rotating angle of a component. With such a device, the operating area of the mechanism can be radially extended or contracted. The mechanism is mainly provided with an oscillating bar 3', an extendable bar 4', a push bar 5, a rotatable bar 6, a connecting bar, a supporting bar 7, and a plurality of fulcrums. In this mechanism, the oscillating bar 3' and rotatable bar 4' respectively have fixed fulcrums and can be oscillated around the fixed fulcrums. The other components are connected to each other by a movable turning shaft, and the oscillating bar 3' changes the rotating angle and radially extends the extendable bar 4'. In case of substituting the extendable bar 4' with an extendable plate, a radially extended area is brought about.