Millions are expected to attend the capital, Manila, the see the pontiff when he arrives on Thursday next week.
Francis Tolentino, a government spokesman in Manila, says around 2,000 traffic officers will have to wear nappies, in case they need to relieve themselves on the job.
He also encouraged the millions who are expected to come and see the pontiff at an open-air Mass on Sunday to wear nappies as well, because there won't be enough portable lavatories to accommodate them.
Mr Tolentino said: "If you attend an event that will last for 24 hours, you cannot go around looking for a [portable lavatory]."
In his second visit to Asia, Pope Francis will visit Sri Lanka from Tuesday to Thursday, before flying to the Philippines for four days.
Last year, the Holy Father visited South Korea.