A knee movement assistive device, comprising: - a waist garment attachable to a user waist and a calf garment attachable to a user calf, said calf garment being arranged along a longitudinal direction (X-X); - an actuator attached to the waist garment and comprising a driver, said driver being configured to switch between an active state, wherein the driver generates a rotational force, and an idle state, wherein the driver generates a null force, the actuator being configured to transform the rotational force of the driver in a tension force; - a transmission cable connecting the actuator to the calf garment and being configured to transmit the tension force, generated by transforming the rotational force of the driver, to the calf garment; said assistive device being configured in that it comprises: - a chain comprising a modular body having a fixed end, attached to the calf garment, a free end and an upper surface connecting the fixed end and the free end, said modular body comprising a groove defined on said upper surface, the transmission cable being slidably channeled in said groove; and wherein: - the chain is configured to switch between an initial configuration, wherein the fixed end and the free end of the modular body are at a first distance, and a limiting configuration, wherein the modular body is arranged along a curvature direction (Y-Y) defining a curvature angle with respect to the longitudinal direction (X-X) such that the fixed end and the free end of the modular body are at a second distance, said second distance being smaller than the first distance, the bending of the user knee switching the modular body of the chain between the initial configuration and the limiting configuration. - a waist garment attachable to a user waist and a calf garment attachable to a user calf, said calf garment being arranged along a longitudinal direction (X-X); - an actuator attached to the waist garment and comprising a driver, said driver being configured to switch between an active state, wherein the driver generates a rotational force, and an idle state, wherein the driver generates a null force, the actuator being configured to transform the rotational force of the driver in a tension force; - a transmission cable connecting the actuator to the calf garment and being configured to transmit the tension force, generated by transforming the rotational force of the driver, to the calf garment; said assistive device being configured in that it comprises: - a chain comprising a modular body having a fixed end, attached to the calf garment, a free end and an upper surface connecting the fixed end and the free end, said modular body comprising a groove defined on said upper surface, the transmission cable being slidably channeled in said groove; - a chain comprising a modular body having a fixed end, attached to the calf garment, a free end and an upper surface connecting the fixed end and the free end, said modular body comprising a groove defined on said upper surface, the transmission cable being slidably channeled in said groove; and wherein: - the chain is configured to switch between an initial configuration, wherein the fixed end and the free end of the modular body are at a first distance, and a limiting configuration, wherein the modular body is arranged along a curvature direction (Y-Y) defining a curvature angle with respect to the longitudinal direction (X-X) such that the fixed end and the free end of the modular body are at a second distance, said second distance being smaller than the first distance, the bending of the user knee switching the modular body of the chain between the initial configuration and the limiting configuration. - the chain is configured to switch between an initial configuration, wherein the fixed end and the free end of the modular body are at a first distance, and a limiting configuration, wherein the modular body is arranged along a curvature direction (Y-Y) defining a curvature angle with respect to the longitudinal direction (X-X) such that the fixed end and the free end of the modular body are at a second distance, said second distance being smaller than the first distance, the bending of the user knee switching the modular body of the chain between the initial configuration and the limiting configuration.