  Let X be a real or complex Banach space and let F in X be a non-empty set. F
is called an existence set of best coapproximation (existence set for brevity),
if for any x in X, $R_F(x)$ is not the empty set, where $$ R_F (x) = \{ d \in F
: \|d-c\| \leq \|x-c\| \hbox{ for any } c \in F \}.$$ It is clear that any
existence set is a contractive subset of X. The aim of this paper is to present
some conditions on F and X under which the notions of exsistence set and
contractive set are equivalent.
