The workers in UD Jaya Group, a small flour producer located in Klaten District, Central Java, Indonesia, complained of having muscle pain or musculoskeletal disorders in the calf, knee, wrist, arm, waist, shoulder, back, and neck because there were variety of activities that required the workers to perform non-ergonomic work postures. This pain resulted in a decrease of work productivity, potentially caused work accidents, and affected the health of the workers. The purpose of the research is to analyze the work postures and to reduce musculoskeletal disorders caused by the non-ergonomic work postures among UDJaya Group workers. In achieving the purpose, a post-work analysis was performed on the work postures and the manual handling processes by using the Rapid Entire Body Assessment (REBA) method and the Manual Activity Chart (MAC) Tool. Based on the REBA assessment on 18 work activities, there was 1 working activity that was classified as an action level 1, 15 working activities were classified as the action level 2, and 2 working activities were classified as the action level 3. Based on the MAC Tool assessment on 11 work activities, 10 working activities were classified as the action level 2 and 1 working activity was classified as the action level 4. The recommendations were to reduce the weight of the load, increase the number of lamps and provide aiding tools.