Nanopores have been proven as versatile single-molecule sensors for individual unlabeled biopolymer detection and characterization. Besides application to next gene sequencing, proteins are becoming a prime target of investigation. In our work, single molecules of bovine serum albumin have been detected as the transient current blockages while the proteins pass through a silicon nitride nanopore. Characterization of transition signals at different biased voltages reveals that globular protein translocating through nanopore is different from the linear DNA, with larger current amplitude and longer transition time due to the protein adsorption with nanopore. The results will shed light on the understanding of protein transport cross an individual biomimetic nuclear pores.