The 19-year-old man from northern Victoria faced the Bendigo Magistrates' Court on Tuesday. He pleaded guilty to 18 charges, including making threats to kill.

The court heard the man was arrested during May this year and interviewed by police.

He told officers he was in a "dangerous state of mind" and willing to carry out a number of threats to kill the woman and her family.

"(These are) some of the most concerning and disturbing threats... from a 19-year-old man that I have heard in some time," magistrate Megan Aumair told the court.

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The man's offending dated back to new year's day, when he pushed the victim over during an argument.

When the woman told the man a few weeks later that the relationship was over he made more than 60 calls to the victim, while also contacting her mother and a friend.

"I'll have the last laugh, dog. You watch," he said in one message to a friend of the victim.

The man was arrested the next day and an intervention order was issued. The court was told that during a police interview, the man admitted contacting the victim "just to p*** her off".

Despite the court order, the man continued to make threats in messages and videos. In April, the court was told, the man threatened to murder the woman and her family if she took screenshots of his messages to police.

"Keep screenshotting yourself to the grave, you dog," he said in one message. The prosecutor told the court the victim was in constant fear.

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She took evidence of the threats to police during May. When officers attended the man's home, he punched a wall and said, "This is why I want her dead."

It was during a police interview that day he said he was willing to carry out his threats.

The defence lawyer told the court the man conceded his behaviour was serious and that he would engage with support programs, including drug and alcohol counselling.

It was the man's first time in custody, the defence lawyer said, and he had entered a plea at an early stage in the proceedings.

Ms Aumair said it was clear the man "has other underlying issues that need addressing" and that the offending was "disturbing, to say the least".

The man was remanded in custody until his next court appearance on June 8.

Officials will assess whether the man can be released under supervision.

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