We prove that a single-valued solution of perfectly competitive TU economies underling nonatomic vector measure market games is uniquely determined as the Mertens [18] value by four plausible valuerelated axioms. Since the Mertens value is always in the core of an economy, this result provides an axiomatization of the Mertens value as a core-selection. Previous works on this matter assumed the economies to be either differentiable (e.g., Dubey and Neyman [7]) or of uniform finite type (e.g., Haimanko [13]). This work does not assume that, thus it contributes to the axiomatic study of payoffs in perfectly competitive economies in general.