Mannosyl ethanolamine and BSA were conjugated together by their amino groups with various homobifunctional cross-linker reagents: disuccinimidyl carbonate (DSC), disuccinimidyl glutarate (DSG), disuccinimidyl suberate (DSS), ethylene glycolbis-(succinimidylsuccinate) (EGS), 1,5-difluoro-2,4-dinitrobenzene (DFDNB), diethyl squarate (DES), and thiophosgene (TP). The resulting mannose-BSA conjugates were subjected to an enzyme-linked lectin assay (ELLA) to investigate their affinity to concanvalin A (ConA). With these results, the seven linkers were evaluated on the basis of five criteria, i.e., cost, reactivity, sugar loading, homogeneity, and affinity to ConA. Thus, DSS, DFDNB, and DES seemed to have advantages over the other cross-linking reagents.