<p>Recently, bipath persistent homology has been proposed as an extension of standard persistent homology, along with its visualization (bipath persistence diagram) and computational methods. In the setting of standard persistent homology, the stability theorem with respect to real-valued functions on a topological space is one of the fundamental results, which gives a mathematical justification for using persistent homology to study noisy data. In proving the stability theorem, the algebraic stability theorem/isometry theorem for persistence modules plays a central role. In this point of view, the stability property for bipath persistent homology is desired for analyzing data. In this paper, we prove the stability theorem of bipath persistent homology with respect to <i>bipath functions</i> on a topological space. This theorem suggests a stability of bipath persistence diagrams: small changes in a bipath function (except at their ends) result in only small changes in the bipath persistence diagram. Similar to the stability theorem of standard persistent homology, we deduce the stability theorem of bipath persistent homology by using the algebraic stability theorem/isometry theorem of bipath persistence modules.</p>