The drop comes amid growing controversy over charges for music tuition in schools across the country.
Numbers have declined steadily in schools across Scotland since 2011 when there were 108 teachers whose main job was to teach music, official Scottish Government figures have shown.
This had dropped to 62 last year, with ten local authority areas having no dedicated music teachers in primary schools at all.
The latest figures represent a drop of three music teachers on 2017, when numbers plummeted to 65 from 79 the previous year.
Earlier this year, Holyrood’s education committee recommended music tuition should be provided free of charge in schools.
In 2018, several councils either introduced or increased fees for instrumental lessons, but MSPs have called for changes to funding for tuition.
Edinburgh, Western Isles, Glasgow and Orkney councils do not charge for lessons.
Dundee and West Dunbartonshire provide free lessons, but charge £85 for instrument hire.
Scottish Conservative spokeswoman for children and young people Alison Harris said: “This is a thoroughly depressing statistic, which highlights the neglect of the SNP government in this area.
“We’re not talking about a statistical blip here. It’s a 42 per cent decrease in the space of seven years.
“That will mean a significantly reduced experience for primary school children all over Scotland.”
She added: “The SNP has been warned for years about how important it is for young children to be given the opportunity to learn a musical instrument, yet it’s allowed teacher numbers in this area to completely collapse.
“If this doesn’t change soon, thousands more youngsters will miss out on opportunities which could shape and influence their entire lives.”
The role of music on the school curriculum has been controversial in recent months over rising levels of tuition fees for instruments charged by councils – some to as high as £524 a year. Some have even started charging for the hire of local authority instruments.
It emerged last week that a crowdfunding bid has been launched to pay for a judicial review of the lawfulness of fees for musical instrument tuition. Ralph Riddiough, a community musician from Ayrshire, is behind the move.
A Scottish Government spokeswoman said: “Teacher numbers in Scottish schools are at their highest since 2010, but we recognise the teacher recruitment challenges.
“That is why we have increased targets for recruitment into initial teacher education and created new routes to make it more practical and flexible for people to access courses
“Music education is of enormous benefit to young people and, as set out in the Programme for Government, we are committed to working corroboratively to find solutions to help ensure instrumental music remains accessible to all.
“The Scottish Government has continued to ensure that our partners in local government receive a fair funding settlement despite further cuts to the Scottish budget from the UK Government.”