Short answer. This article's text does not say. Article 246 defines parricide as killing one's father, mother, or child — legitimate or illegitimate — or any ascendant, descendant, or spouse, but it does not use the word adoptive, so whether an adoptive parent or adopted child counts under this article cannot be confirmed from this text alone.
What the law says
Any person who shall kill his father, mother, or child, whether legitimate or illegitimate, or any of his ascendants or descendants, or his spouse, shall be guilty of parricide and shall be punished by the penalty of reclusion perpetua to death.
Revised Penal Code, Article 246 — Parricide: Killing A Relative. Read the full provision →
What the text of Article 246 actually says
Article 246 defines parricide as applying to any person who shall kill his father, mother, or child, whether legitimate or illegitimate, or any of his ascendants or descendants, or his spouse. The relationships named are father, mother, child, ascendant, descendant, and spouse — categories that, on the face of the text, describe family relationships without the word adoptive appearing anywhere in the article.
Why illegitimate does not answer the adoption question
The phrase whether legitimate or illegitimate addresses a child's status relative to the parents' marriage — a child born within marriage versus outside it — which is a different concept from adoption. An adopted child is not, by that fact alone, either a legitimate or illegitimate biological child of the adopter under this wording; the article's legitimate-or-illegitimate language does not by itself extend the parricide definition to adoptive relationships.
What this page cannot confirm
Whether killing an adoptive parent or an adopted child is charged as parricide, rather than under some other article, is a question this specific text does not answer. Answering it correctly would require looking at whether other legislation or another part of the Code defines child, ascendant, or descendant to include adoptive relationships for purposes of this article — material this page does not have in front of it, so no conclusion is drawn here. That restraint is deliberate: parricide is a distinct crime with its own penalty, and pinning that label on a relationship the text does not name would be asserting law this page cannot verify.
The penalty this article carries, for what it's worth
For relationships that do fall within Article 246 as written, the penalty is reclusion perpetua to death. Republic Act No. 9346 (2006) prohibits imposing the death penalty in the Philippines, so where the Revised Penal Code's own terminology is used, reclusion perpetua takes the place of death. This penalty information does not, however, resolve whether an adoptive relationship brings a killing within this article in the first place.