Protection device for the personal protection of a user, wherein said device includes a mattress body including a plurality of inflatable elements , arranged adjacent and side-by-side in sequence, wherein each inflatable element has an elongated envelope shape so as to define an internal chamber shaped like a channel, and wherein the mattress body is able to assume a first deflated rest configuration in which the inflatable elements are in a deflated condition arranged close to each other or stacked on top of each other, and wherein the mattress body is able to assume a second active inflated configuration, and wherein - said inflatable elements have, in said second active inflated configuration, a linear and/or straight form; the protection device is characterized in that - each of the inflatable elements has at least one first side wall connected adheringly to a second side wall of an adjacent inflatable element so as to define at least one adherence zone , and - each of the inflatable elements has two further opposite sides , and - wherein in said sequence of inflatable elements the opposite sides of the inflatable elements define opposite external surfaces of the mattress body , wherein the opposite external surfaces include a surface or wall exposed to an impact or to the cold, and a rear wall facing the user, and wherein said adherence zone between the first side wall of an inflatable element and the second side wall of an adjacent inflatable element acts as a tie member between the two opposite external surfaces so as to control a mattress-like form of the mattress body in the second active inflated configuration, and wherein each of the inflatable elements includes at least two sheets joined together along a perimeter so as to define a perimetral joining edge and wherein, along, or in a direction of, said sequence of adjacent inflatable elements , each adherence zone between the first side wall of the inflatable element and the second side wall of the adjacent inflatable element alternates with a perimetral joining edge of the two sheets of a same inflatable element so as to define a concertina or bellows structure. - said inflatable elements have, in said second active inflated configuration, a linear and/or straight form; the protection device is characterized in that - each of the inflatable elements has at least one first side wall connected adheringly to a second side wall of an adjacent inflatable element so as to define at least one adherence zone , and - each of the inflatable elements has two further opposite sides , and - wherein in said sequence of inflatable elements the opposite sides of the inflatable elements define opposite external surfaces of the mattress body , wherein the opposite external surfaces include a surface or wall exposed to an impact or to the cold, and a rear wall facing the user, and wherein said adherence zone between the first side wall of an inflatable element and the second side wall of an adjacent inflatable element acts as a tie member between the two opposite external surfaces so as to control a mattress-like form of the mattress body in the second active inflated configuration, and wherein each of the inflatable elements includes at least two sheets joined together along a perimeter so as to define a perimetral joining edge and wherein, along, or in a direction of, said sequence of adjacent inflatable elements , each adherence zone between the first side wall of the inflatable element and the second side wall of the adjacent inflatable element alternates with a perimetral joining edge of the two sheets of a same inflatable element so as to define a concertina or bellows structure. <EOS>