A key challenge for the visual system entails the extraction of constant properties of objects from sensory information that varies moment by moment due to changes in viewing conditions. Although successful performance in constancy tasks requires cooperation between perception and working memory, the function of the memory system has been under-represented in recent material perception literature. Here, we addressed the limits of material constancy by elucidating if and how working memory is involved in constancy tasks by using a variety of material stimuli, such as metals, glass, and translucent objects. We conducted experiments with a simultaneous and a successive matching-to-sample paradigm in which participants matched the perceived material properties of objects with or without a temporal delay under varying illumination contexts. The current study combined a detailed analysis of matching errors, data on the strategy use obtained via a self-report questionnaire, and the statistical image analysis of diagnostic image cues used for material discrimination. We found a comparable material constancy between simultaneous and successive matching conditions, and it was suggested that, in both matching conditions, participants used similar information processing strategies for the discrimination of materials. The study provides converging evidence on the critical role of working memory in material constancy, where working memory serves as a shared processing bottleneck that constrains both simultaneous and successive material constancy. Material constancy in perception and working memory To illustrate the appearance of objects or goods seen around us, we commonly use descriptions, such as glossiness, roughness, or transparency. Recently, perception and recognition of material properties or, more broadly, "shitsukan" (the sense of quality; Komatsu & Goda, 2018) is gaining increased interest in vision science. Although our understanding of material perception is advancing (see Fleming, 2017; Komatsu & Goda, 2018; Schmid & Doerschner, 2019 for recent reviews), it remains a challenging domain. The visual system must detect specific visual features that are diagnostic of particular materials (Fleming, 2014) to achieve perceptual stability, or constancy, in response to changes in viewing conditions. However, the degree of constancy varies depending on illumination, object shape, and viewing angle (e.g. see Chadwick & Kentridge, 2015 for a review of gloss constancy). How the human brain accomplishes (and sometimes fails in) material constancy remains a subject of debate that primarily focuses on the mechanism by which the visual system extracts perceptual properties of material information from low and mid-level image features (Anderson, 2020; Nishida, 2019). In contrast, the role of working memory in material constancy has so far been rarely investigated. Successful performance in constancy tasks requires cooperation between perceptual and memory systems. For example, an individual engaging in foraging activity, and search...