This production method for a composite shaped product having an undercut portion is able to readily manufacture a composite shaped product having a complicated shape having an undercut portion, by including: a step (i) of forming an impregnated precursor by heating and pressurizing a non-impregnated precursor including carbon fibers with an average fiber length of 1 to 100 mm and a thermoplastic resin; a step (ii) of heating the impregnated precursor at the melting point of the thermoplastic resin or more; a step (iii) of arranging the heated impregnated precursor into a mold having an undercut structure; a step (iv) of clamping the undercut structure after or simultaneously being operated and pressurizing the impregnated precursor; and a step (v) of unclamped the mold, re-operating the undercut structure and taking out the composite shaped material from the unclamped mold.