A heat exchanger of a ventilating system, including heat exchange plates which are laminated at a predetermined interval, first vibration members which are laminated among the heat exchange plates, for generating turbulence in outdoor air passing through a first air path, being aligned in the first air path through which the outdoor air passes and second vibration members for generating turbulence in the indoor air passing through a second air path, while being aligned in the second air path through which indoor air passes, can improve heat transfer performance by increasing turbulence of air by positioning a mesh type heat exchange in a air path through which outdoor and indoor air passes.