Arrivals from South Korea, the Philippines' largest source market, went down 21% from the same period last year to 1.13 million recorded through November, according to data from the Department of Tourism.
Arrivals from China, which remains the fifth-largest source market, also fell 16.55% year-on-year to 248,000.
A series of incidents involving the deaths of South Korean and Japanese tourists has raised safety concerns about travel to the Philippines.
The Filipino government has previously pledged to strengthen safety measures for foreign tourists, according to the Philippine News Agency.
The Philippines also resumed its e-visa program for Chinese nationals from November to revive its tourism industry after nearly two years of suspension.
Thailand recorded over 30 million foreign tourists as of November while Vietnam welcomed over 19 million.