This technical note discusses a contact-force control problem for a flexible arm. This flexible arm includes a Timoshenko beam, and thus we call it the flexible Timoshenko arm. The aim of the force control is to control the contact force at the contact point. To solve this problem, we propose a simple boundary controller and show the exponential stability of the closed-loop system by the frequency domain method. Finally, we describe simulation results carried out to investigate the validity of the proposed controller for the force control problem.