This paper is concerned with a category theoretic treatment of the realization theory of a basic linear system. In order to make a categorical problem of the realization we introduced two categories, the category of basic linear functional systems BLFS and that of basic linear dynamical systems BLDS, in addition to the category of basic linear systems BLS defined in another paper. The BLFS corresponds to a class of so-called“experiments”and is formulated as a category by extracting conditions when an experiment can be modeled into a basic linear system. The BLDS corresponds to a class of state space representations of basic linear systems and, similarly, their essential properties are extracted to be formulated as a category. Based on these categories, it was shown that two functors, a realization functor F₁: BLFS→BLS and a representation functor F₂: BLS→BLDS exist. It was also shown that F₁ and F₂ yield a universal and a co-universal map with respect to their corresponding forgetful functors G₁: BLS→BLFS and G₂: BLDS→BLS, respectively and that those maps correspond to categorical representations of controllability and observability. Finally, a category theoretic meaning of a minimum realization of a basic linear system is discussed.