A stabilizer leg device with a stabilizer leg to be moved down-wards from an object so as to stabilize the object by bearing through a foot plate (7) on the ground. The device comprises a first engagement member (20) arranged coaxially to a horizontal axis on a part (19) fixed in relation to the object, and a shaft (12) having a first end provided with a second engagement member (21) and an opposite second end arranged to be influenced by movement of a second stabilizer leg member in relation to a first stabilizer leg member to make the shaft slide along the stabilizer leg under extension and retraction of the stabilizer leg so as to cause pivoting of the stabilizer leg by a mutual engagement of said engagement members (20, 21). Members (16, 17) guiding the shaft are designed to automatically unlock and lock, respectively, the stabilizer leg with respect to possibility to pivot about said horizontal axis by passing a predetermined position by the second stabilizer leg member upon retraction and extension of the stabilizer leg.