A pixel circuit (PC) for an organic light-emitting display apparatus comprising: a driving transistor (T1) configured to control an amount of electric current flowing to an organic light-emitting diode (OLED) from a power voltage line (PL); a compensation transistor (T3) configured to diode-connect the driving transistor (T1) in response to a voltage applied to first and second compensation gate electrodes (G3-1, G3-2) of the compensation transistor (T3); and a gate insulating layer between the compensation gate electrodes (G3-1, G3-2) and a compensation active region (A3) of the compensation transistor (T3), wherein layer structure of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region (A3) is different from a layer structure of the gate insulating layer between the second compensation gate electrode (G3-2) and the compensation active region (A3), wherein a first compensation portion of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region (A3) 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 (A3) 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 (T1) configured to control an amount of electric current flowing to an organic light-emitting diode (OLED) from a power voltage line (PL); a compensation transistor (T3) configured to diode-connect the driving transistor (T1) in response to a voltage applied to first and second compensation gate electrodes (G3-1, G3-2) of the compensation transistor (T3); and a gate insulating layer between the compensation gate electrodes (G3-1, G3-2) and a compensation active region (A3) of the compensation transistor (T3), wherein layer structure of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region (A3) is different from a layer structure of the gate insulating layer between the second compensation gate electrode (G3-2) and the compensation active region (A3), wherein a first compensation portion of the gate insulating layer between the first compensation gate electrode (G3-1) and the compensation active region (A3) 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 (A3) 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 . <EOS>