A court in Japan on Monday sentenced a man to death for the murder of 19 people in a stabbing attack at a care home for disabled people.

Satoshi Uematsu, 30, had not denied his involvement in the grisly 2016 rampage, one of the country's worst mass killings, but his lawyers had entered a "not guilty" plea, arguing he was suffering a "mental disorder" linked to drug use.

But chief judge Kiyoshi Aonuma dismissed the argument and ruled Uematsu deserved no leniency.

"The lives of 19 people were taken away. This is profoundly grave," he told the court.

Uematsu had planned the murders and he had "an extreme intention to kill", the judge said.

Satoshi Uematsu did not deny involvement in the grisly attack that killed 19 people at a care home
Satoshi Uematsu did not deny involvement in the grisly attack that killed 19 people at a care home JIJI PRESS / STR

"There is no room for leniency."

The judge added there were strong calls for punishment from the families of those killed in the attack.

"We considered the accused didn't have a previous record and we made a careful consideration, but we demand the death penalty," the judge said.

Uematsu had said before the verdict that he would not appeal, whatever the decision, though he argued he did not deserve to be executed.

He showed no apparent reaction as the sentence was announced.