Short answer. Possibly, but not for every falsehood. The offence punishes publishing false news that may endanger public order or damage the interest or credit of the State. Ordinary mistakes, gossip and false claims about private persons fall outside it, though other laws may still apply.
What the law says
Any person who by means of printing, lithography, or any other means of publication shall publish or cause to be published as news any false news which may endanger the public order, or cause damage to the interest or credit of the State
Revised Penal Code, Article 154 — False News And Unlawful Utterances. Read the full provision →
The narrow target of the offence
Three elements have to line up. The material must be published as news — presented as fact, not as opinion, satire or a question. It must be false. And it must be of a kind that may endanger the public order, or cause damage to the interest or credit of the State. That last element is what most people miss. A false post about a neighbour, an ex-partner or a business rival does not become this crime merely by being false and widely shared; the harm the provision is aimed at is public disorder or damage to the State's standing. Falsehoods about private individuals are dealt with by the separate law on libel and by civil claims for damages.
The current penalty, and why the figures matter
The penalty is arresto mayor together with a fine of ₱40,000 to ₱200,000. Those peso amounts are the ones fixed by Republic Act No. 10951 (2017), which revised fines and property values throughout the Revised Penal Code. This is worth stating plainly because a great many websites, old textbooks and even reprinted copies of the Code still carry the 1930 figures, which are dramatically lower and no longer the law. If a source you are reading gives a different fine for this article, check which version of the Code it is reproducing before you rely on it for anything.
The other three acts in the same article
The provision is broader than its popular name suggests. Alongside false news it punishes encouraging disobedience to the law or to the constituted authorities, and praising, justifying or extolling an act punished by law. It also reaches maliciously publishing an official resolution or document without proper authority or before it has been officially published — a real risk for anyone who circulates a leaked draft order. Finally, it covers printing or distributing books, pamphlets, periodicals or leaflets that do not bear the real printer's name or that are classified as anonymous. Sharers, printers and distributors, not just authors, can find themselves within its reach.
If you are the one who shared it
Being wrong is not the same as being criminally liable, and the burden of proving every element rests on the prosecution. Preserve what you actually posted, where you got it and when you took it down, because a prompt, visible correction is relevant to how the matter is assessed. Do not quietly delete the record; that removes the evidence that may help you. Bear in mind that separate statutes on cybercrime, libel and, in specific emergencies, other special laws can apply to the same conduct. Whether any of them fits your situation depends on facts this general explanation cannot know.