Minimizing the environmental load and cost throughout the product lifecycle requires appropriate lifecycle design as well as product design. Product lifecycle can be designed easily by describing lifecycle scenario at an early stage and the product should be designed to realize the scenario. This paper proposes a modular design method that links lifecycle scenario to appropriate modular structure by unifying components applicable to the same lifecycle option, such as recycling, maintenance, reuse, and upgrading. Appropriate modular structures may differ with the lifecycle options, meaning that while the modular structure for recycling should be based on the type of material, the structure for upgrading should be based on the lifetime of components. The modules, therefore, can undergo lifecycle processes without disassembly into components. These may lead to easy management of components throughout the lifecycle and increase the efficiency of recovery processes and logistics in resource circulation. We also propose an evaluation method of modular product from the viewpoint of resource efficiency. For the evaluation, we formalize the probability that each module goes through preferable lifecycle paths designated by the scenario in order to represent the advantage of modularization. This paper also illustrates a case study in order to discuss effectiveness of the proposed method.