can foreigners invest in the Philippine Stock Market?

of course! there are industries in the Philippines such as mining which allows for a certain percentage of their common stocks to be owned by foreigners. as long as the companies adhere to the maximum, which is usually 40%, then they are ok.
in www.pse.com.ph when each of the listed companies are analyzed (in the corporate information tab in the site), the maximum foreign ownership in percentage is listed. so if you are a foreigner who wants to diversify his or her portfolio and wants to include emerging markets such as the Philippines, then by all means you can. the only requirement is know where you are betting your money into.