A method for assembling a wind turbine tower on an erection foundation, in which method at least two ring elements, as high as part of the tower, are composed from concrete segments and the ring elements are lifted into a superimposed position in the order of assembly, characterized in, that - the first ring element, on an assembly table in a multifunctional carriage, is lifted in an upright position to the vertical position of the next ring element using locking collars climbing up along frame guide columns of an assembly device and locked at that height using a locking ring of the assembly device, the multifunctional carriage and the assembly table are taken down with the help of the locking collars, and the multifunctional carriage repositions assembly table and leaves to pick up a new ring element - the following ring elements, on an assembly table in a multifunctional carriage, are placed individually in the assembly order below the previous ring element, lifted with the aid of the locking collars into contact with the ring element above and attached to each other, the ring elements are lifted, with the previous ring element or the ring elements, the height of the next ring element using the locking collars, and locked at that height, the multifunctional carriage and the assembly table are taken down with the help of the locking collars, and the multifunctional carriage repositions assembly table and leaves to pick up a new ring element, - the last ring element, on an assembly table in a multifunctional carriage, is lifted using the locking collars into contact with the previous ring element and released connected together to a suspended state, the multifunctional carriage and the assembly table are taken down with the help of locking collars and moved outside the tower, - the locking collars are locked to the lowest ring element, and - the superimposed ring elements are lowered with the aid of the locking collars onto the erection foundation. - the first ring element, on an assembly table in a multifunctional carriage, is lifted in an upright position to the vertical position of the next ring element using locking collars climbing up along frame guide columns of an assembly device and locked at that height using a locking ring of the assembly device, the multifunctional carriage and the assembly table are taken down with the help of the locking collars, and the multifunctional carriage repositions assembly table and leaves to pick up a new ring element - the following ring elements, on an assembly table in a multifunctional carriage, are placed individually in the assembly order below the previous ring element, lifted with the aid of the locking collars into contact with the ring element above and attached to each other, the ring elements are lifted, with the previous ring element or the ring elements, the height of the next ring element using the locking collars, and locked at that height, the multifunctional carriage and the assembly table are taken down with the help of the locking collars, and the multifunctional carriage repositions assembly table and leaves to pick up a new ring element, - the last ring element, on an assembly table in a multifunctional carriage, is lifted using the locking collars into contact with the previous ring element and released connected together to a suspended state, the multifunctional carriage and the assembly table are taken down with the help of locking collars and moved outside the tower, - the locking collars are locked to the lowest ring element, and - the superimposed ring elements are lowered with the aid of the locking collars onto the erection foundation.