An internal-combustion engine control device, comprising: a variable compression ratio means for changing an engine compression ratio of an internal combustion engine; a turbocharger driven by exhaust gas of the internal combustion engine for supercharging intake air; an ignition device for spark-igniting a mixture in each combustion chamber of the internal combustion engine; and a control means for controlling the engine compression ratio and ignition timing based on at least a required load (tT) of the internal combustion engine, the control means being configured to: execute a steady-state control mode when in a steady state, wherein the steady-state control mode is configured to set the engine compression ratio to a steady-state engine compression ratio setpoint (εm) and set the ignition timing to a steady-state ignition timing setpoint (Tm) in accordance with a value of the required load (tT); wherein the control means is characterized by further being configured to execute an acceleration-transient-state control mode when in a transient state from a non-supercharged state to a supercharged state, wherein the transient state occurs owing to a rise in the required load (tT), wherein the acceleration-transient-state control mode is configured to correct and set the engine compression ratio to a transient-state compression ratio setpoint (εh) and concurrently correct and set the ignition timing to a transient-state ignition timing setpoint (Th) in accordance with the value of the required load (tT), and wherein the transient-state compression ratio setpoint (εh) is higher than the steady-state engine compression ratio setpoint (εm) and the transient-state ignition timing setpoint (Th) is more retarded than the steady-state ignition timing setpoint (Tm). a variable compression ratio means for changing an engine compression ratio of an internal combustion engine; a turbocharger driven by exhaust gas of the internal combustion engine for supercharging intake air; an ignition device for spark-igniting a mixture in each combustion chamber of the internal combustion engine; and a control means for controlling the engine compression ratio and ignition timing based on at least a required load (tT) of the internal combustion engine, the control means being configured to: execute a steady-state control mode when in a steady state, wherein the steady-state control mode is configured to set the engine compression ratio to a steady-state engine compression ratio setpoint (εm) and set the ignition timing to a steady-state ignition timing setpoint (Tm) in accordance with a value of the required load (tT); wherein the control means is characterized by further being configured to execute an acceleration-transient-state control mode when in a transient state from a non-supercharged state to a supercharged state, wherein the transient state occurs owing to a rise in the required load (tT), wherein the acceleration-transient-state control mode is configured to correct and set the engine compression ratio to a transient-state compression ratio setpoint (εh) and concurrently correct and set the ignition timing to a transient-state ignition timing setpoint (Th) in accordance with the value of the required load (tT), and wherein the transient-state compression ratio setpoint (εh) is higher than the steady-state engine compression ratio setpoint (εm) and the transient-state ignition timing setpoint (Th) is more retarded than the steady-state ignition timing setpoint (Tm). execute a steady-state control mode when in a steady state, wherein the steady-state control mode is configured to set the engine compression ratio to a steady-state engine compression ratio setpoint (εm) and set the ignition timing to a steady-state ignition timing setpoint (Tm) in accordance with a value of the required load (tT); wherein the control means is characterized by further being configured to execute an acceleration-transient-state control mode when in a transient state from a non-supercharged state to a supercharged state, wherein the transient state occurs owing to a rise in the required load (tT), wherein the acceleration-transient-state control mode is configured to correct and set the engine compression ratio to a transient-state compression ratio setpoint (εh) and concurrently correct and set the ignition timing to a transient-state ignition timing setpoint (Th) in accordance with the value of the required load (tT), and wherein the transient-state compression ratio setpoint (εh) is higher than the steady-state engine compression ratio setpoint (εm) and the transient-state ignition timing setpoint (Th) is more retarded than the steady-state ignition timing setpoint (Tm).