Container made of a plastic material, provided with a base including a standing ring forming a support flange and a diaphragm extending from the standing ring to a central portion, said diaphragm being capable of standing in an outwardly-protruding position, said container defining an inner volume to be filled with a product, wherein the diaphragm connects to the standing ring at an outer junction forming an outer articulation of the diaphragm with respect to the standing ring; wherein the diaphragm connects to the central portion at an inner junction forming an inner articulation of the diaphragm with respect to the central portion; whereby said diaphragm is invertible with respect to the standing ring from the outwardly-protruding position, in which the inner junction extends below the outer junction, to an inwardly-protruding position, in which the inner junction extends above the outer junction; characterized in that said diaphragm has, in the inwardly-protruding position, the outer portion having a concavity turned inwards with respect to the inner volume of the container, whereas the inner portion has a concavity turned outwards with respect to the inner volume of the container, and in that, in the outwardly-protruding position of the diaphragm, the central portion stands above the standing ring of the container, said standing ring having a frusto-conical inner wall joining the support flange and the diaphragm, wherein the inner wall has a top end, which forms the outer junction, and the diaphragm has: - an outer portion, which connects to the standing ring and is curved in radial section, said outer portion having a concavity turned outwards with respect to the inner volume of the container, and - an inner portion, which connects to the outer portion and to the central portion and is curved in radial section, said inner portion having a concavity turned inwards with respect to the inner volume of the container. wherein the diaphragm connects to the standing ring at an outer junction forming an outer articulation of the diaphragm with respect to the standing ring; wherein the diaphragm connects to the central portion at an inner junction forming an inner articulation of the diaphragm with respect to the central portion; whereby said diaphragm is invertible with respect to the standing ring from the outwardly-protruding position, in which the inner junction extends below the outer junction, to an inwardly-protruding position, in which the inner junction extends above the outer junction; characterized in that said diaphragm has, in the inwardly-protruding position, the outer portion having a concavity turned inwards with respect to the inner volume of the container, whereas the inner portion has a concavity turned outwards with respect to the inner volume of the container, and in that, in the outwardly-protruding position of the diaphragm, the central portion stands above the standing ring of the container, said standing ring having a frusto-conical inner wall joining the support flange and the diaphragm, wherein the inner wall has a top end, which forms the outer junction, and the diaphragm has: - an outer portion, which connects to the standing ring and is curved in radial section, said outer portion having a concavity turned outwards with respect to the inner volume of the container, and - an inner portion, which connects to the outer portion and to the central portion and is curved in radial section, said inner portion having a concavity turned inwards with respect to the inner volume of the container. - an outer portion, which connects to the standing ring and is curved in radial section, said outer portion having a concavity turned outwards with respect to the inner volume of the container, and - an inner portion, which connects to the outer portion and to the central portion and is curved in radial section, said inner portion having a concavity turned inwards with respect to the inner volume of the container.