The invention relates to a drilling-resistance measuring device (10) and to a method for material testing in a humid environment or underwater. The drilling-resistance measuring device (10) comprises a housing (1), in which a drive and a drill chuck (3) coupled to the drive are arranged, in which drill chuck a drilling needle (4) is or can be releasably held, wherein the housing (1) has a drilling-needle outlet opening (5′) enclosed by a drilling-needle outlet guide (5), through which drilling-needle outlet opening the drilling needle (4) extends out of the housing (1). The drilling-resistance measuring device (10) comprises at least one water-tight bellows (6), which is arranged in the interior of the housing (1) around the drilling needle (4) between the drill chuck (3) and the drilling-needle outlet guide (5), wherein moisture or water can enter the bellows (6) through the drilling-needle outlet opening (5′).