The security officials say the attack happened on Thursday outside the city of al-Arish.
They say the bomber slowly approached the checkpoint, waited for soldiers and policemen to start searching the car before he blew himself and his vehicle up. Five other people were wounded.
The officials spoke on condition of anonymity in line with regulations.
Islamic militants have been attacking security forces in Sinai for years but the frequency of the attacks has dramatically grown since the ouster of Islamist President Mohammed Morsi in a July coup.
The army and police are waging a campaign against the militants in northern Sinai.
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