An oscillator for density measurement of a liquid, including a counter mass and a container for the liquid. The oscillator is made of metal and the container has two identical resonator tubes, which are clamped into the counter mass in parallel to each other, and a connecting tube connecting the resonator tubes. The resonator tubes can be set into a resonance oscillation in which a common centre of gravity of the resonator tubes remains at rest during the resonance oscillation. The oscillator also includes a web located between the counter mass and the connecting tube, which web spaces the resonator tubes from each other in such a way that the lengths (L) of the resonator tubes enclosed between the counter mass and the web can be set into a diametrically opposite oscillation on the basis of which the density of the liquid located in the oscillator can be determined.