Police responded to an emergency called placed by the Swedish man's girlfriend on Monday, arriving to find the man dead in his apartment in Taoyuan City.
The man was found with two stab wounds to his neck, and blood was spilt all over the apartment, according to the China Post newspaper.
Three blood stained knives were confiscated from the apartment, with the Swedish man's girlfriend being arrested after police found she was emotionally unstable and evasive under interrogation, according to the paper.
The woman denies the crime.
The foreign ministry has confirmed the death and notified the man's relatives, but was unwilling to divulge any further information.
“A local crime investigation is underway but I cannot say more for the time being,” Linn Duvhammar of the foreign ministry told the TT news agency.
Neighbours told police that they had heard “heated quarrels” coming from the home before the police arrived, and surveillance cameras indicate that no one besides the victim and his girlfriend entered the apartment.