This paper proposed a chopstick-type gripper for a meal-assistance robot, which is capable of adapting its shape and the contact force with the target food according to the size and the elasticity of the food. Solely using position control of the driving motor for the mechanism, this feature was enabled without relying on force sensors. The gripper was designed based on the concept of under-actuation and a planar mechanism with 2 DOF composed of a combination of 2 four-bar mechanisms having a torsion spring in a passive joint. To clarify the gripping motion and relationship among the contact force, food’s size and elasticity, a simulation based on kineto-elasto-static analysis was performed. Finally, to verify the theoretical analysis, a simple prototype was manufactured and an experiment to measure the contact force has been conducted.