Currently available ß-lactamase inhibitors have an inadequate effect against ß-lactamases, which continue to increase constantly. There is a need for novel ß-lactamase inhibitors which can be used in the treatment of bacterial infections caused by resistant bacteria that are currently difficult to treat and that produce: class C ß-lactamase; extended-spectrum ß-lactamase (ESBL) belonging to classes A and D; KPC-2, which decomposes even carbapenem, the last bastion of ß-lactam antibiotics, belonging to class A; and the like. Provided are a compound shown by formula (I), a method for producing the same, a ß-lactamase inhibitor, and a method for treating bacterial infections.