An injector injection amount control device (18, 218, 318), comprising: an acquisition section configured to acquire a measured value of a crank angle that is a rotation angle of a crankshaft of an engine; a determination section configured to determine instruction injection amounts of fuel from respective injectors, the respective injectors corresponding to a plurality of cylinders of the engine; an estimation section configured to estimate a torque arising in each of the plurality of cylinders of the engine based on a non-linear Kalman filter employing an error between the measured value of the crank angle acquired by the acquisition section and an estimate value of the crank angle, wherein: the estimation section is further configured to predict the crank angle at a next timing, predict the crank angular velocity at the next timing, and predict the torque at the next timing according to a non-linear formula including a term relating to inertia of a piston crank mechanism of the engine, a term relating to gravity of the piston crank mechanism, a term relating to angular velocity of the piston crank mechanism, and a term relating to friction in the piston crank mechanism in the non-linear Kalman filter, which is input with a measured value of the crank angle at a current timing, a calculated value of the crank angular velocity at the current timing, and a value of the torque at the current timing; and a correction section configured to correct the instruction injection amounts for the respective injectors corresponding to the plurality of cylinders such that each of the plurality of torques estimated by the estimation section falls within the same range. an acquisition section configured to acquire a measured value of a crank angle that is a rotation angle of a crankshaft of an engine; a determination section configured to determine instruction injection amounts of fuel from respective injectors, the respective injectors corresponding to a plurality of cylinders of the engine; an estimation section configured to estimate a torque arising in each of the plurality of cylinders of the engine based on a non-linear Kalman filter employing an error between the measured value of the crank angle acquired by the acquisition section and an estimate value of the crank angle, wherein: the estimation section is further configured to predict the crank angle at a next timing, predict the crank angular velocity at the next timing, and predict the torque at the next timing according to a non-linear formula including a term relating to inertia of a piston crank mechanism of the engine, a term relating to gravity of the piston crank mechanism, a term relating to angular velocity of the piston crank mechanism, and a term relating to friction in the piston crank mechanism in the non-linear Kalman filter, which is input with a measured value of the crank angle at a current timing, a calculated value of the crank angular velocity at the current timing, and a value of the torque at the current timing; and a correction section configured to correct the instruction injection amounts for the respective injectors corresponding to the plurality of cylinders such that each of the plurality of torques estimated by the estimation section falls within the same range.