Glucocerebrosidase (GCase) is localized in lysosome and degrades glucocerebroside into glucose and ceramide. It has been reported that a decrease in GCase activity by mutations is one of the risk factors of Parkinson's disease (PD) via the accumulation of α-synuclein. In addition, the accumulation of α-synuclein impairs protein degradation via autophagy-lysosomal pathway (ALP). ALP is classified into macroautophagy (MA), microautophagy (mA) and chaperone-mediated autophagy (CMA). Recent reports revealed that Hsc70, a mA- and CMA-related protein, is decreased in PD patients, suggesting the involvement of mA and CMA in PD pathogenesis. We have established a novel method to assess mA and CMA activities in cultured cells. In the present study, we investigated whether the inhibition of GCase affects mA/CMA activity using this method. Conduritol-β-epoxide (CβE), a GCase inhibitor, did not affect mA/CMA activity in AD293 cells. However, CβE significantly decreased it in cells transfected with α-synuclein. These findings suggest that the inhibition of GCase impairs mA/CMA activity in the presence of α-synuclein, leading to further accumulation of α-synuclein. The impairment of mA/CMA would be related to PD pathogenesis.