Device for measuring the resistance to ground penetration, commonly called a penetrometer, and comprising at least one measuring rod having a measuring point (4, 5) at its end, at least one outer protective tube arranged around said measuring rod, down-feed and lifting means that allow driving the couple formed by said protective tube and said measuring rod in the ground in static mode, percussion means that allow driving the couple formed by said protective tube and said measuring rod in the ground in dynamic mode, and measuring means that allow determining the penetration resistance of said ground, the device being characterized in that: - said protective tube is arranged around said measuring rod with a clearance that allows for a free sliding of the measuring rod with respect to the protective tube and vice-versa, - said down-feed and lifting means comprise at least one actuator arranged to move in vertical translation a mobile beam wherein a central shaft is mounted, arranged to transfer the down-feed and lifting effort to said protective tube, - said central shaft can move with respect to said mobile beam on a determined stroke, - said percussion means are loaded on said mobile beam and comprise at least one hammer arranged to hit an anvil integral with said central shaft arranged to transfer the percussion effort to said protective tube so that the percussion efforts in dynamic mode are transmitted directly to said protective tube without passing through said measuring rod, - said central shaft is mounted in said mobile beam through a mounting block that comprises said measuring means and wherein the central shaft is slidingly mounted, said mounting block comprising a compression chamber delimited between a fixed section and a mobile section, and - said central shaft comprises an axial recess to receive partly said measuring rod that is coupled to said mobile section by locking means, said locking means having two positions, one called locked, wherein the measuring rod is coupled with the mobile section, which allows measuring in static mode at least the cone resistance (qc) whatever the static or dynamic drive-in mode, and the other called free, wherein the measuring rod is uncoupled from said mobile section. - said protective tube is arranged around said measuring rod with a clearance that allows for a free sliding of the measuring rod with respect to the protective tube and vice-versa, - said down-feed and lifting means comprise at least one actuator arranged to move in vertical translation a mobile beam wherein a central shaft is mounted, arranged to transfer the down-feed and lifting effort to said protective tube, - said central shaft can move with respect to said mobile beam on a determined stroke, - said percussion means are loaded on said mobile beam and comprise at least one hammer arranged to hit an anvil integral with said central shaft arranged to transfer the percussion effort to said protective tube so that the percussion efforts in dynamic mode are transmitted directly to said protective tube without passing through said measuring rod, - said central shaft is mounted in said mobile beam through a mounting block that comprises said measuring means and wherein the central shaft is slidingly mounted, said mounting block comprising a compression chamber delimited between a fixed section and a mobile section, and - said central shaft comprises an axial recess to receive partly said measuring rod that is coupled to said mobile section by locking means, said locking means having two positions, one called locked, wherein the measuring rod is coupled with the mobile section, which allows measuring in static mode at least the cone resistance (qc) whatever the static or dynamic drive-in mode, and the other called free, wherein the measuring rod is uncoupled from said mobile section.