An electromechanical transducer transducing an electric signal into mechanical vibration, the electromechanical transducer comprising: a structural unit in which at least one pair of magnets (15 to 18), a yoke (12, 13) conducting magnetic flux generated by the magnets, and a coil supplied with the electric signal are integrally arranged; an armature including an inner portion disposed to pass through an internal space of the structural unit and first and second outer portions (19b, 19c) protruding on both sides in a first direction from the inner portion, the armature constituting a magnetic circuit with the structural unit via two regions through which components of the magnetic flux flow in directions opposite to each other in the inner portion and being displaced in a displacement direction based on a magnetic force of the magnetic circuit; a first elastic unit (20, 21) giving a restoring force to the first outer portion in response to displacement of the armature, the first elastic unit (20, 21) being held between the first outer portion and the structural unit; and a second elastic unit (22, 23) giving a restoring force to the second outer portion in response to displacement of the armature, the second elastic unit (22, 23) being held between the second outer portion and the structural unit, characterized in that the armature has a shape in which a cross-sectional area at a predetermined position between the two regions is smaller than a cross-sectional area at the two regions, and magnetic flux flowing in the first direction in the armature is saturated within a range of displacement of the armature, and a ratio Sm /Sm max of an absolute value Sm of a negative stiffness based on the magnetic force of the magnetic circuit in the vicinity of a balanced position of the armature to a maximum absolute value Sm max of said negative stiffness within the range of displacement of the armature is larger than 0.9. a structural unit in which at least one pair of magnets (15 to 18), a yoke (12, 13) conducting magnetic flux generated by the magnets, and a coil supplied with the electric signal are integrally arranged; an armature including an inner portion disposed to pass through an internal space of the structural unit and first and second outer portions (19b, 19c) protruding on both sides in a first direction from the inner portion, the armature constituting a magnetic circuit with the structural unit via two regions through which components of the magnetic flux flow in directions opposite to each other in the inner portion and being displaced in a displacement direction based on a magnetic force of the magnetic circuit; a first elastic unit (20, 21) giving a restoring force to the first outer portion in response to displacement of the armature, the first elastic unit (20, 21) being held between the first outer portion and the structural unit; and a second elastic unit (22, 23) giving a restoring force to the second outer portion in response to displacement of the armature, the second elastic unit (22, 23) being held between the second outer portion and the structural unit, characterized in that the armature has a shape in which a cross-sectional area at a predetermined position between the two regions is smaller than a cross-sectional area at the two regions, and magnetic flux flowing in the first direction in the armature is saturated within a range of displacement of the armature, and a ratio Sm /Sm max of an absolute value Sm of a negative stiffness based on the magnetic force of the magnetic circuit in the vicinity of a balanced position of the armature to a maximum absolute value Sm max of said negative stiffness within the range of displacement of the armature is larger than 0.9.