Biological accumulation is the process in which the amount of chemical accumulates in organisms to make its concentration in the body higher than its external environment. These are two processes at two different biological levels influencing the bioaccumulation. One is a physiological process, in which an organism may change its absorb, transform or egestion rates in respond to the change in its internal chemical condition. It is known that an organism may control its internal chemical concentration to maintain the homeostasis. The other is an ecosystem-level process, where the chemical concentration in a body changes as the organic material is transferred from a species to a species through the food web. Although these two processes may interact each other, only a few researches have performed a theoretical analysis. Here, using simple mass-balance model that incorporates both physiological and ecological processes, we examined how the chemical concentration in organisms may respond to a change in the environmental chemical concentration and how it depends on the trophic level and physiological characteristics of the organism. This model predicts that the strength of homeostasis at individual levels has a strong influence on the effect of ecosystem-level patterns in bioaccumulation.