<p>Disclosed is an EBNA1 function inhibitor in which a compound represented by formula (1), a salt thereof or a hydrate or solvate of this compound or salt has an inhibiting action on the binding of EBNA1 proteins and virus genome DNA. In other words, the compound, salt thereof or hydrate or solvate of this compound or salt have an inhibiting action on the DNA binding capacity of EBNA1 proteins and are therefore are useful as EBNA1 protein function inhibitors.</p>
