A multilayer printed wiring board manufacturing method including forming conductor posts, which are of substantially uniform thickness and with which the top surfaces are protected by a resist, on a conductor pattern disposed on an upper surface of a build-up layer formed on a core substrate, shaping the conductor posts to have a constriction by adjusting the time of immersion in an etching solution that etches the conductor posts, forming a low elastic modulus layer of substantially the same height as the conductor posts after removing the resist at the top surfaces, and forming mounting electrodes on upper surfaces of the conductor posts.