Device for replacing a pallet, supporting the bottom face of a load, with a second pallet replacing the first; said device comprises: - a slide surface element having a flat face assigned to static and sliding abutment with a lateral face of the load; - a translating support element defining an elongated flat surface or face assigned to abut with the side-by-side pallets (P, S) and provided with pallet gripping elements; such flat face of the translating support element is perpendicular to the flat face of the slide surface element; - a control element of the load sliding having a face parallel to the translating support element and assigned to meet with a face of the load opposite the respective bottom; - a connecting element which rigidly constrains the slide surface element and which constrains the translating support element to translate linearly on its geometric plane in the direction of its longitudinal axis or to translate in parallel direction to said face of the slide surface element; where the control element of the load sliding is connected to the slide surface element and/or to the connecting element; - a rotation member connected to the connecting element to allow the rotation of the latter around a rotation axis, parallel to at least the flat face of the translating support element, between an initial condition, in which the slide surface element and the translating support element are respectively vertical and horizontal, and a pallet replacement condition in which they (3, 5) are rotated by more than 90° and vice versa; - a member with a base structure member, assigned to be fixed on a horizontal floor and connected to the connecting element by means of the rotation member in a way that the respective rotation axis is horizontal and at a height with respect to the floor such as to allow that at least in the initial condition the slide surface element and the translating support element are respectively vertical and horizontal and to allow free rotation of the connecting element, and of what is fixed or connected to it, at least up to the replacement condition of the pallet and vice versa; said device being characterized in that it further comprises a rotation actuator of the linear or rotary type interposed between the structure member and the connecting element for the rotation of the latter; and in that the translating support element is directly or indirectly connected to the connecting element by means of a set of slide guides and at least one linear actuator or linear damper where such slide guides and the actuator or damper are parallel to each other, to the longitudinal development of the translating support element and to the translation direction of the translating support element which they (15, 17) define. - a slide surface element having a flat face assigned to static and sliding abutment with a lateral face of the load; - a translating support element defining an elongated flat surface or face assigned to abut with the side-by-side pallets (P, S) and provided with pallet gripping elements; such flat face of the translating support element is perpendicular to the flat face of the slide surface element; - a control element of the load sliding having a face parallel to the translating support element and assigned to meet with a face of the load opposite the respective bottom; - a connecting element which rigidly constrains the slide surface element and which constrains the translating support element to translate linearly on its geometric plane in the direction of its longitudinal axis or to translate in parallel direction to said face of the slide surface element; where the control element of the load sliding is connected to the slide surface element and/or to the connecting element; - a rotation member connected to the connecting element to allow the rotation of the latter around a rotation axis, parallel to at least the flat face of the translating support element, between an initial condition, in which the slide surface element and the translating support element are respectively vertical and horizontal, and a pallet replacement condition in which they (3, 5) are rotated by more than 90° and vice versa; - a member with a base structure member, assigned to be fixed on a horizontal floor and connected to the connecting element by means of the rotation member in a way that the respective rotation axis is horizontal and at a height with respect to the floor such as to allow that at least in the initial condition the slide surface element and the translating support element are respectively vertical and horizontal and to allow free rotation of the connecting element, and of what is fixed or connected to it, at least up to the replacement condition of the pallet and vice versa;