Alzheimer's disease (AD) is a disorder in which cognitive dysfunction appears due to neuronal damage caused by abnormal aggregation of amyloid-beta protein (Aβ) in the brain. The number of patients is increasing year by year, not only in Japan but also around the world. However, all drugs currently approved in Japan for the treatment of AD are symptomatic treatments and cannot fundamentally cure the condition. Therefore, establishing methods of prevention and therapeutic of AD is an important issue. The authors have shown that porcine liver decomposition product (PLDP) exhibit a variety of biological activities in living organisms. In this study, we evaluated the effect of PEL, lipids extracted from PLDP, on the aggregation process of Aβ, a key protein in AD. PEL was extracted from PLDP by the Bligh & Dyer method. The thioflavin T assay was used as the evaluation method to monitor changes over time in fluorescence caused by Aβ aggregation. The results revealed that PEL dissociates as Aβ aggregates. In addition, the thioflavin T assay was also performed on various lysophospholipids, which are abundant in PEL. The results confirmed the phenomenon of inhibition of Aβ aggregation in certain molecular species. These results suggest that PEL could be a first step in the development of AD drug discovery.