Method for determining an attention level of a driver of a motor vehicle, comprising the following steps: i) a plurality of successive values (Γ d ( k)) of an actual quantity (Γ d) representative of a control action of the driver of the motor vehicle on a driving member of this vehicle are acquired in a first time interval, ii) a type of road (TR(k)) on which the motor vehicle is being driven is determined at successive time intervals, and it is verified whether said type of road (TR(k)) has changed since the preceding interval, and iii) the attention level of the driver is determined depending on said acquired values (Γ d ( k)), and also depending on the result of the verification of a change in the type of road (DTR(k)), wherein, prior to step iii): - a target quantity (Γ̂ d) representative of an action that the driver would perform on said driving member if the attention level of the driver were high is determined at a plurality of times in said first time interval, - said target quantity (Γ̂ d) and said actual quantity (Γ d) are compared, at each of these times, by computing a difference (TPE(k)) between said actual quantity (Γ d) and said target quantity (Γ̂ d), - a reference effective value (VE L (k)) is computed from said differences (TPE(k)) computed during the first time interval, - the differences computed during a second time interval shorter than the first time interval and included therein are selected, - a short-time effective value (VE C (k)) of said selected differences (TPE(k)) is computed, and - said short-time effective value (VE C (k)) is compared to said reference effective value (VE L (k)), and wherein, in step iii), the attention level of the driver is determined depending on the result of the comparison of said short-time effective value (VE C (k)) to said reference effective value (VE L (k)). i) a plurality of successive values (Γ d ( k)) of an actual quantity (Γ d) representative of a control action of the driver of the motor vehicle on a driving member of this vehicle are acquired in a first time interval, ii) a type of road (TR(k)) on which the motor vehicle is being driven is determined at successive time intervals, and it is verified whether said type of road (TR(k)) has changed since the preceding interval, and iii) the attention level of the driver is determined depending on said acquired values (Γ d ( k)), and also depending on the result of the verification of a change in the type of road (DTR(k)), wherein, prior to step iii): - a target quantity (Γ̂ d) representative of an action that the driver would perform on said driving member if the attention level of the driver were high is determined at a plurality of times in said first time interval, - said target quantity (Γ̂ d) and said actual quantity (Γ d) are compared, at each of these times, by computing a difference (TPE(k)) between said actual quantity (Γ d) and said target quantity (Γ̂ d), - a reference effective value (VE L (k)) is computed from said differences (TPE(k)) computed during the first time interval, - the differences computed during a second time interval shorter than the first time interval and included therein are selected, - a short-time effective value (VE C (k)) of said selected differences (TPE(k)) is computed, and - said short-time effective value (VE C (k)) is compared to said reference effective value (VE L (k)), and wherein, in step iii), the attention level of the driver is determined depending on the result of the comparison of said short-time effective value (VE C (k)) to said reference effective value (VE L (k)). - a target quantity (Γ̂ d) representative of an action that the driver would perform on said driving member if the attention level of the driver were high is determined at a plurality of times in said first time interval, - said target quantity (Γ̂ d) and said actual quantity (Γ d) are compared, at each of these times, by computing a difference (TPE(k)) between said actual quantity (Γ d) and said target quantity (Γ̂ d), - a reference effective value (VE L (k)) is computed from said differences (TPE(k)) computed during the first time interval, - the differences computed during a second time interval shorter than the first time interval and included therein are selected, - a short-time effective value (VE C (k)) of said selected differences (TPE(k)) is computed, and - said short-time effective value (VE C (k)) is compared to said reference effective value (VE L (k)), and wherein, in step iii), the attention level of the driver is determined depending on the result of the comparison of said short-time effective value (VE C (k)) to said reference effective value (VE L (k)).