In recent years, there have been intensive theoretical research works on modeling/analysis of oscillatory phenomena. In this paper, we derive a sufficient condition under which (a large number of) linearly coupled piecewise affine systems show an oscillatory behavior called Y-oscillation. It is known that the analysis of PWA systems is difficult due to their switching nature. An important feature of the obtained result is that, under the assumption that every subsystem has a specific property in common, the criteria can be rewritten in terms of coupling topology in an easily checkable way so that it is applicable to large scale systems. For an illustrative purpose, we analyze the well-known FitzHugh-Nagumo equation that is a model for a neural oscillator in mathematical physiology. Categories and Subject Descriptors I.2.8 [Artificial Intelligence]: Problem Solving, Control Methods, and Search--control theory General Terms Theory, Algorithms Keywords piecewise affine systems, oscillati...