Magistrate Hugh Radford said he needed to send a strong message of deterrence to the offender, 64-year-old David Jones, and protect the community when imposing his sentence.

"The circumstances of the offending to say the least are gross. Masturbating on a bus in front of someone is a very low act in my view and should be denounced in the strongest terms," he sad.

Mr Radford said he also took into account the fear and distress the victim would have felt.

Jones sat three rows behind the middle-aged woman while travelling on a bus in Ballarat before moving to the row of seats next to her across the middle aisle.

He began rubbing his groin area in view of the victim and put his hands inside his pants for a few seconds while looking at her.

Jones continued touching himself outside his clothing while looking at the victim for eight minutes.

He pleaded guilty to the offending at the Ballarat Magistrates' Court early in May and was sentenced on Tuesday.

"This offence carries a maximum term of imprisonment of five years jail. That is how important parliament considers the court must take these matters," Mr Radford said.

The court heard Jones had seven criminal convictions for similar offending spanning a period of more than 20 years and was last sentenced to imprisonment in 2002.

"This will be your eighth offence for similar conduct. The likelihood of re-offending in my view is therefore high," Mr Radford said.

"In the circumstances I have to set a penalty and sentence that is not only going to protect the community but deter you from carrying on in this way in the future."

The court heard a psychologist found Jones had expressed remorse for his offending and experienced feelings of shame and grief over his criminal history and psycho sexual problems.

He also experienced depression and problems with alcohol abuse.

Jones was sentenced to three months' imprisonment and a 24-month community corrections order with requirements to undergo supervision and treatment and rehabilitation for alcohol abuse.

He was also placed on the sex offender's register for eight years.

Jones was taken into custody from the court room on Tuesday morning but granted appeal bail later that afternoon.

His appeal will be heard in the County Court.

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