A low-profile module in which the component mounting density is increased to achieve high performance is provided. Despite achieving high performance in the module (100) by mounting components such as a semiconductor substrate (104) and chip components (105) on both main surfaces (101a, 101b) of a circuit board (101), by making the thickness (Ha) of a first component layer (102), which is formed by mounting the semiconductor substrate (104) alone face down on one main surface (101a) of the circuit board (101), thinner than the thickness of a second component layer (103), which is formed by mounting a plurality of chip components (105) on the other main surface (101b) of the circuit board (101), a low-profile module (100) in which the component mounting density is increased to achieve high performance can be provided.