Device for stimulating the genital or erogenous areas of a person, comprising: - an inflatable and deformable ball delimiting an interior space (E int) and an exterior space (E ext), said ball having a first position, termed resting position, in which the ball is essentially spherical, and a second position, termed deformed position, in which the ball is no longer essentially spherical, - at least one stimulation element (2, 3, 13, 23) comprising a first portion configured so as to be able to penetrate inside the anus or the vagina of a person seated on said ball and a second portion (3, 13, 23) designed to bear, at least indirectly, against a supporting surface on which said ball rests during normal use of the device, said second portion preferably being hermetically fixed to the internal wall (Si) of said ball, - at least one receptacle arranged in said interior space (E int) and having an internal cavity able to contain, at least in part, said first portion, said receptacle having at least one first end hermetically fixed to the internal wall (Si) of said ball, said first end defining an upper opening through which said first portion can pass, at least in part, and at least one second end defining a lower opening through which said second portion (3, 13, 23) can pass, at least in part, said internal cavity extending between said first end and said second end and defining a chamber which is not pressurized, that is to say at atmospheric pressure, of said interior space (E int) which communicates with the exterior space (E ext) through said upper opening and which is separated from a pressurized chamber of said interior space (E int), said receptacle and/or said second portion (3, 13, 23) being configured so as to avoid any transfer of fluid between said pressurized chamber and said non-pressurized chamber, and said ball, said stimulation element (2, 3, 13, 23) and said receptacle being configured such that the ratio Rv, defined by the formula: Rv = volume of the first portion 2 positioned in the exterior space E ext / total volume of the first portion 2, increases when the ball passes from its rest position to its deformed position. - an inflatable and deformable ball delimiting an interior space (E int) and an exterior space (E ext), said ball having a first position, termed resting position, in which the ball is essentially spherical, and a second position, termed deformed position, in which the ball is no longer essentially spherical, - at least one stimulation element (2, 3, 13, 23) comprising a first portion configured so as to be able to penetrate inside the anus or the vagina of a person seated on said ball and a second portion (3, 13, 23) designed to bear, at least indirectly, against a supporting surface on which said ball rests during normal use of the device, said second portion preferably being hermetically fixed to the internal wall (Si) of said ball, - at least one receptacle arranged in said interior space (E int) and having an internal cavity able to contain, at least in part, said first portion, said receptacle having at least one first end hermetically fixed to the internal wall (Si) of said ball, said first end defining an upper opening through which said first portion can pass, at least in part, and at least one second end defining a lower opening through which said second portion (3, 13, 23) can pass, at least in part, said internal cavity extending between said first end and said second end and defining a chamber which is not pressurized, that is to say at atmospheric pressure, of said interior space (E int) which communicates with the exterior space (E ext) through said upper opening and which is separated from a pressurized chamber of said interior space (E int),