A power-up signal generating circuit of a semiconductor memory apparatus includes a current source unit configured to supply a current to a first node; a current sink unit configured to be turned on when the level of a divided voltage dividing an external voltage is equal to or higher than a predetermined level to allow the current to flow from a first node to a second node; a control unit configured to control the turn-on timing of the current sink unit by controlling a voltage level of the second node; and a signal generating unit configured to enable a power-up signal depending on a voltage level of the first node.