Mr Abe, who was 67, bled to death after sustaining two deep wounds, a doctor from Nara Medical University Hospital says.
A man suspected of shooting dead former Japanese prime minister Shinzo Abe has admitted the crime, police have said.
Mr Abe, 67, was shot twice from behind while giving a speech at a campaign rally in the western city of Nara.
He bled to death after sustaining two deep neck wounds that damaged an artery.
It is the first assassination of a sitting or former Japanese premier since the 1930s.
Named in media reports as 41-year-old Yamagami Tetsuya, the gunman appeared unemotional when talking to investigators and has been responding calmly to questions.
Background of Abe’s suspected assassin emerges – live updates
Explosives have been found at the unemployed suspect’s home and officers are recommending that nearby residents evacuate.
Pictures from the scene show what appears to be a homemade firearm. It was made of a mix of materials including metal and wood, police said.
It remains unclear whether the parts for it were bought on the internet and if it was made on a 3D printer.
An image isolated on video appears to show him moments before the shooting took place.
Dressed in a grey T-shirt and beige trousers, he was wrestled to the ground by police.
He told investigators he spent three years working for Japan’s Maritime Self-Defence Force.
According to state broadcaster NHK, he told police he was unhappy with Mr Abe and intended to kill him.
But Kyodo News said he had not been motivated by a grudge against Mr Abe’s political beliefs.
0:35 Play Video – Man suspected of shooting Shinzo Abe arrested. Man suspected of shooting Shinzo Abe arrested
Major damage to the heart
Mr Abe had no vital signs when he arrived at Nara Medical University Hospital and was never revived after suffering major damage to his heart.
More than 100 units of blood were given during four hours of blood transfusions as Mr Abe haemorrhaged.
Mr Abe held his chest as he collapsed, his shirt smeared with blood. NHK showed footage of security guards running towards him.
A puff of white smoke was seen as he made a campaign speech outside a railway station ahead of elections to Japan’s upper house on Sunday.
A reporter at the scene said they heard two consecutive bangs during Mr Abe’s address.
