A sewage discharge device for a variable type water-saving flush toilet, comprising: a toilet body installed on a floor or a wall, the toilet body including a flushing water inlet port formed therein so as to allow for inflow of flushing water flowing through a flushing water inflow passage into which the flushing water is introduced from the outside, a bowl opened at a top thereof and configured to store a certain amount of sewage therein, a connection tube configured to discharge sewage from the bowl, and a cover part configured to cover a rear portion of the bowl and to allow sewage discharged through the connection tube to be induced to a bottom tube; a corrugated tube connected to the connection tube, the corrugated tube being configured to form a flow path of sewage drained from the bowl and being capable of bent in one direction; a flushing water branching unit fluidically connected with the flushing water inflow passage and configured to allow a part of the flushing water flowing through the flushing water inflow passage to be branched when the flushing water is introduced into the bowl; a sewage discharge tube comprising: a main discharge tube connected to the corrugated tube and configured to discharge sewage to the outside; and an auxiliary tank disposed on an outer circumferential surface of the main discharge tube and configured to store therein flushing water branched from the flushing water branching unit and supplied thereto, the auxiliary tank having an auxiliary discharge hole formed thereon to allow flushing water stored in a lower portion thereof to be drained, wherein when the flushing water branched from the flushing water branching unit reaches a preset amount, the auxiliary tank is downwardly moved by its own weight so that sewage is discharged to the outside through the main discharge tube, and the time during which sewage is discharged to the outside through the main discharge tube is delayed in proportion to a discharge speed at which the flushing water supplied to the auxiliary tank is drained through the auxiliary drain hole; and an elastic unit configured to elastically interconnect the connection tube and the sewage discharge tube, and to allow the sewage discharge tube to be oriented in an upright state by an elastic force of the elastic unit upon the interruption of the supply of flushing water. a toilet body installed on a floor or a wall, the toilet body including a flushing water inlet port formed therein so as to allow for inflow of flushing water flowing through a flushing water inflow passage into which the flushing water is introduced from the outside, a bowl opened at a top thereof and configured to store a certain amount of sewage therein, a connection tube configured to discharge sewage from the bowl, and a cover part configured to cover a rear portion of the bowl and to allow sewage discharged through the connection tube to be induced to a bottom tube; a corrugated tube connected to the connection tube, the corrugated tube being configured to form a flow path of sewage drained from the bowl and being capable of bent in one direction; a flushing water branching unit fluidically connected with the flushing water inflow passage and configured to allow a part of the flushing water flowing through the flushing water inflow passage to be branched when the flushing water is introduced into the bowl; a sewage discharge tube comprising: a main discharge tube connected to the corrugated tube and configured to discharge sewage to the outside; and an auxiliary tank disposed on an outer circumferential surface of the main discharge tube and configured to store therein flushing water branched from the flushing water branching unit and supplied thereto, the auxiliary tank having an auxiliary discharge hole formed thereon to allow flushing water stored in a lower portion thereof to be drained, wherein when the flushing water branched from the flushing water branching unit reaches a preset amount, the auxiliary tank is downwardly moved by its own weight so that sewage is discharged to the outside through the main discharge tube, and the time during which sewage is discharged to the outside through the main discharge tube is delayed in proportion to a discharge speed at which the flushing water supplied to the auxiliary tank is drained through the auxiliary drain hole; and an elastic unit configured to elastically interconnect the connection tube and the sewage discharge tube, and to allow the sewage discharge tube to be oriented in an upright state by an elastic force of the elastic unit upon the interruption of the supply of flushing water.