A safety valve for a compressed gas storage tank (12) includes a relief conduit (16, 18) provided for fluid connection to an interior chamber (14) of the compressed gas storage tank (12), and a closing member (22) sealing the relief conduit (16, 18); a retaining device (24) being provided which, in a normal condition, locks the closing member (22) in place and which, in safety-critical conditions, opens a cross-sectional flow area (30) in such a manner that the relief conduit (16, 18) is open to the atmosphere. In accordance with the present invention, the closing member (22) is connected to an adjustor (26) which adjusts the cross-sectional flow area (30) of the relief conduit (16, 18) as a function of an upstream interior pressure.