Link mechanisms play a crucial role in mechanical systems, such as automobiles and robots, responsible for transforming input motions into various output motions. Some link mechanisms possess multiple degrees of freedom with multiple inputs, and others have multiple outputs. Designing multi-input/output link mechanisms to achieve the desired target motion solely through the ingenuity of a designer is a challenging problem. In contrast, compliant mechanisms, which leverage elastic deformation for work transformation, have explored displacement transformation mechanisms with multiple inputs and outputs, designed through the topology optimization of the structure [1]. Similarly, this study focuses on synthesizing a multi-input/output linkage mechanism using the topology optimization method. The advantage of synthesizing the mechanism through topology optimization is that it not only optimizes the arrangement of parts but also simultaneously reduces the weight of each part structure. The weight reduction of each part in the link mechanism is expected to lead to improved controllability and energy efficiency. We propose an approach to topology optimization for a multi-input/multi-output link mechanism that achieves the desired motion, utilizing a continuum approximation model of the link mechanism with micropolar elasticity introduced in our previous work [2]. To obtain the optimal solution for the linkage mechanism that follows the target motion with the appropriate degrees of freedom, we minimize the error function of the target displacement of the output part, under the constraints of strain energy and load addition. The topology optimization problem is numerically implemented based on the Solid Isotropic Material with Penalization (SIMP) method and applied to several numerical examples. REFERENCES [1] B. Zhu, Q. Chen, M. Jin and X. Zhang. Design of fully decoupled compliant mechanisms with multiple degrees of freedom using topology optimization. Mechanism and Machine Theory, 126:413–428, 2018. [2] Y. Sayo and T. Yamada, Conceptual design method of link mechanisms based on topology optimization and concept of micropolar continuum theory, Transactions of the JSME(in Japanese), 89(927):23-00082, 2023.