We consider the uncertainty relation between position and momentum of
a particle on S1 (a circle). Since S1 is compact, the uncertainty of p
osition must be bounded. Consideration on the uncertainty of position
demands delicate treatment. Recently Ohnuki and Kitakado have formulat
ed quantum mechanics on S(D) (a D-dimensional sphere). Armed with thei
r formulation, we examine this subject. We also consider parity and fi
nd a phenomenon similar to the spontaneous symmetry breaking. We discu
ss problems which we encounter when we attempt to formulate quantum me
chanics on a general manifold.