Forklifts are used in factories and warehouses to transport and load cargo. As the number of forklifts increases over a wide area, many fatal accidents (e.g., contact with workers, falling loads, and tipping over of the main unit) have been reported. There is an urgent need in the industry to reduce these fatal accidents. The purpose of this paper is to develop a detailed model of a forklift to establish indicators for detecting hazardous conditions of forklifts. Few previous studies have included hydraulic cylinder models in their analyses, and this paper proposes a motion modeling and analysis focusing on hydraulic cylinder models.