In this paper, we consider a resolvent problem arising in the study of a Korteweg-type model of isothermal compressible viscous fluids derived by Dunn and Serrin (1985), and we prove resolvent estimates in bounded and exterior domains. The Korteweg-type model is employed to describe fluid capillarity effects or a liquid-vapor two-phase flow with phase transition as diffuse interface model. Our resolvent problem is obtained from a linearized system of the Korteweg-type model around the steady state (ρ, u) = (1, 0), where ρ is the fluid density and u is the fluid velocity. For bounded domains, we treat variable coefficients and prove that the resolvent set contains C + = {z ∈ C : z ≥ 0} under the condition that the pressure function P (ρ) satisfies not only P (1) ≥ 0 but also P (1) < 0, where P (1) = (dP/dρ)(1). We follow the idea of Kotschote (2014) to handle P (1) < 0. For exterior domains, we treat constant coefficients and prove that the resolvent set contains {z ∈ C + : |z| ≥ δ} for any δ > 0 when P (1) ≥ 0. Furthermore, we introduce a global solvability result for the nonlinear problem in a bounded domain as an application of the resolvent estimate.