Nouns ending in -ment are masculine.
The suffix often marks an action or result derived from a verb.
Is parlement masculine or feminine?
leparlement
The rule behind it
99.6% of -ment nouns are masculine
In context
La loi a été approuvée par le parlement.
The law has gone through parliament.
Le gouvernement tomba après un vote au parlement.
The government collapsed after a vote in parliament.
La réforme a été abrogée par le Parlement.
The reform was repealed by the Parliament.