Riding the strength of its growing residential loan portfolio, Territorial Bancorp Inc. posted an 18 percent increase in first-quarter earnings and said it will increase its dividend for the second time in three months.

The parent of the state’s fifth-largest bank said today that net income last quarter rose to $3.5 million, or 34 cents a share, from $3 million, or 26 cents a share, in the year-earlier period. Its loans receivable increased 9 percent to $711.5 million from $652.5 million a year ago as it originated more loans.

Territorial also boosted its dividend 10 percent to 11 cents a share from 10 cents a share. It will be payable June 1 to shareholders of record as of May 18. In February, Territorial boosted its dividend to 10 cents a share from 9 cents a share.