Interpreting the coordinates of the quantum Euclidean space _q⁴ [the SO_q(4)-covariant noncommutative space] as the entries of a ``q-quaternion matrix'' we construct (anti)instanton solutions of a would-be q-deformed su(2) Yang-Mills theory on <sub>q</sub><sup>4</sup>. Since the (anti)selfduality equations are covariant under the quantum group of deformed rotations, translations and scale change, by applying the latter we can respectively generate ``gauge equivalent'' or ``inequivalent'' solutions from the one centered at the origin and with unit size. We also construct multi-instanton solutions. As these solutions depend on noncommuting parameters playing the roles of `sizes' and `coordinates of the centers' of the instantons, this indicates that the moduli space of a complete theory should be a noncommutative manifold. Similarly, as the (global) gauge transformations relating ``gauge equivalent'' solutions depend on the generators of two copies of SU_q(2), this suggests that gauge transformations should be allowed to depend on additional noncommutative parameters.