A steering control device, comprising: a command value calculation circuit that calculates a command value (I*) for a power source that generates power to be applied to a steering mechanism of a vehicle, based on a first controlled variable (I as1 *) and a second controlled variable (I as2 *) which are calculated based on a plurality of kinds of state quantities (V, τ, dτ, ωs, θs) indicating a steering state of a steering mechanism, wherein, the command value calculation circuit includes a first control circuit that calculates the first controlled variable (I as1 *) based on a first state quantity that meets a required level of reliability out of the plurality of kinds of state quantities (V, τ, dτ, ωs, θs), characterized in that, the command value calculation circuit further includes a first processing circuit that performs a first limiting process of setting, for each first state quantity, a first limiting value (I UL *, I LL *) that limits a range of variation in the first controlled variable (I as1 *) according to the first state quantity, and limiting the range of variation in the first controlled variable (I as1 *) based on the first limiting value (I UL *, I LL *), and a second control circuit that calculates a basic component of the second controlled variable (I as2 *) based on a second state quantity that does not meet the required level of reliability out of the plurality of kinds of state quantities (V, τ, dτ, ωs, θs), and a second processing circuit that performs a second limiting process of limiting a range of variation in the basic component by using a predetermined second limiting value (I th), and calculates the second controlled variable (I as2 *) based on the basic component subjected to the second limiting process. a command value calculation circuit that calculates a command value (I*) for a power source that generates power to be applied to a steering mechanism of a vehicle, based on a first controlled variable (I as1 *) and a second controlled variable (I as2 *) which are calculated based on a plurality of kinds of state quantities (V, τ, dτ, ωs, θs) indicating a steering state of a steering mechanism, wherein, the command value calculation circuit includes a first control circuit that calculates the first controlled variable (I as1 *) based on a first state quantity that meets a required level of reliability out of the plurality of kinds of state quantities (V, τ, dτ, ωs, θs), characterized in that, the command value calculation circuit further includes a first processing circuit that performs a first limiting process of setting, for each first state quantity, a first limiting value (I UL *, I LL *) that limits a range of variation in the first controlled variable (I as1 *) according to the first state quantity, and limiting the range of variation in the first controlled variable (I as1 *) based on the first limiting value (I UL *, I LL *), and a second control circuit that calculates a basic component of the second controlled variable (I as2 *) based on a second state quantity that does not meet the required level of reliability out of the plurality of kinds of state quantities (V, τ, dτ, ωs, θs), and a second processing circuit that performs a second limiting process of limiting a range of variation in the basic component by using a predetermined second limiting value (I th), and calculates the second controlled variable (I as2 *) based on the basic component subjected to the second limiting process. a first control circuit that calculates the first controlled variable (I as1 *) based on a first state quantity that meets a required level of reliability out of the plurality of kinds of state quantities (V, τ, dτ, ωs, θs), characterized in that, the command value calculation circuit further includes a first processing circuit that performs a first limiting process of setting, for each first state quantity, a first limiting value (I UL *, I LL *) that limits a range of variation in the first controlled variable (I as1 *) according to the first state quantity, and limiting the range of variation in the first controlled variable (I as1 *) based on the first limiting value (I UL *, I LL *), and a second control circuit that calculates a basic component of the second controlled variable (I as2 *) based on a second state quantity that does not meet the required level of reliability out of the plurality of kinds of state quantities (V, τ, dτ, ωs, θs), and a second processing circuit that performs a second limiting process of limiting a range of variation in the basic component by using a predetermined second limiting value (I th), and calculates the second controlled variable (I as2 *) based on the basic component subjected to the second limiting process.