A pixel circuit for an organic light-emitting display apparatus comprising: a driving transistor configured to control an amount of electric current flowing to an organic light-emitting diode (OLED) from a power voltage line; a compensation transistor configured to diode-connect the driving transistor in response to a voltage applied to first and second compensation gate electrodes (G3-1, G3-2) of the compensation transistor; and a gate insulating layer between the compensation gate electrodes (G3-1, G3-2) and a compensation active region of the compensation transistor, wherein layer structure of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region is different from a layer structure of the gate insulating layer between the second compensation gate electrode (G3-2) and the compensation active region, wherein a first compensation portion of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region has a single-layer structure, and a second compensation portion of the gate insulating layer between the second compensation gate electrode (G3-2) and the compensation active region has a multi-layer structure, wherein the second compensation portion includes a first layer including a material that is included in the first compensation portion, characterized in that the second compensation portion further includes a second layer including a material that is different from the material included in the first compensation portion, wherein the material included in the second layer has a dielectric constant that is greater than the dielectric constant of the material included in the first layer. a driving transistor configured to control an amount of electric current flowing to an organic light-emitting diode (OLED) from a power voltage line; a compensation transistor configured to diode-connect the driving transistor in response to a voltage applied to first and second compensation gate electrodes (G3-1, G3-2) of the compensation transistor; and a gate insulating layer between the compensation gate electrodes (G3-1, G3-2) and a compensation active region of the compensation transistor, wherein layer structure of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region is different from a layer structure of the gate insulating layer between the second compensation gate electrode (G3-2) and the compensation active region, wherein a first compensation portion of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region has a single-layer structure, and a second compensation portion of the gate insulating layer between the second compensation gate electrode (G3-2) and the compensation active region has a multi-layer structure, wherein the second compensation portion includes a first layer including a material that is included in the first compensation portion, characterized in that the second compensation portion further includes a second layer including a material that is different from the material included in the first compensation portion, wherein the material included in the second layer has a dielectric constant that is greater than the dielectric constant of the material included in the first layer.