In this paper, we study for the first time the stability of the inverse source problem for the biharmonic operator with a compactly supported potential in R 3 . Firstly, to connect the boundary data with the unknown source, we shall consider an eigenvalue problem for the bi-Schr: odinger operator ∆ 2 `V pxq on a ball which contains the support of the potential V . We prove a Weyl-type law for the upper bounds of spherical normal derivatives of both the eigenfunctions φ and their Laplacian ∆φ corresponding to the bi-Schr: odinger operator. This type of upper bounds was proved by Hassell and Tao for the Schr: odinger operator. Secondly, we investigate the meromorphic continuation of the resolvent of the bi-Schr: odinger operator and prove the existence of a resonance-free region and an estimate of L 2 comp
´L2loc type for the resolvent. As an application, we prove a bound of the analytic continuation of the data from the given data to the higher frequency data. Finally, we derive the stability estimate which consists of the Lipschitz type data discrepancy and the high frequency tail of the source function, where the latter decreases as the upper bound of the frequency increases.