A method of folding up a table, which includes two tabletop panels, two leg frames foldably mounted at the tabletop panels respectively, and two connecting joints pivotally coupled between the tabletop panels respectively for enabling the tabletop panels to be pivotally folded between a folded condition and an unfolded condition, wherein a pivotal movable gap is formed at each of the connecting joints to enable a pivotal movement the tabletop panels to be pivotally folded between the folded condition and the unfolded condition, includes the steps of (a) pivotally folding the tabletop panels to the unfolded condition; and (b) locking up the pivotal movement between the tabletop panels in the unfolded condition for preventing a lateral movement of each of the connecting joints through the pivotal movable gap thereof.