The maintenance of public toilets, such as those found in convenience stores, presents challenges in the era of limited human resources. Consequently, the development of an automatic toilet cleaning system is necessary. The detection of trash on the toilet floor is an essential component of the automatic toilet cleaning system. However, this process presents its own set of challenges, including the unpredictability of the types and locations of the trash that may be present. This study proposes a system for detecting solid waste on the toilet floor by applying the structure and feature similarity index method of image. The difference in the structure and features of the reference and actual images can indicate the trash that appears on the toilet floor. This study also proposes a method for determining the threshold value of similarity feature measurement. The experimental results demonstrate that the proposed detection system is able to produce a detection success rate of up to 96.5%. Additionally, the system proves capable of detecting small objects, such as human hair, under specific conditions. This method offers a resource-efficient solution to the challenges faced in maintaining public toilet cleanliness.

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