The TES poll found just one in five teachers is very confident about their music teaching compared to 85 per cent who feel at ease teaching maths and 80 per cent English.
This lack of confidence in music was the same across all age groups of teachers.
Dr Janet Mills of the Royal College of Music said: "There is no reason why teachers cannot be as confident in music as they are in maths if they had the same amount of help. But it is so difficult for teachers when confronted with specialists with particular skills to see how they can get the same results from children."
The lack of confidence in music may be one reason why so few primary teachers - just 20 of the 500 questioned - said that they were very confident in teaching all subjects. But teachers have become increasingly confident in computer technology.
The 2001 Office for Standards in Education report on primary teaching found that teachers' subject knowledge was weakest in ICT, although the proportion of schools with good or better teaching in ICT was rising, due partly to New Opportunities Fund training - being undertaken by more than two-thirds of teachers.
The poll suggests some 40 per cent of primary teachers are now very confident in ICT, and a further 44 per cent are fairly confident.
Professor Ted Wragg, of Exeter University, has conducted studies in past years asking how competent teachers feel in each subject.
He said that it was significant that the "batting order" had hardly changed since 1991, with teachers still feeling most confident about maths and English and least confident about music.
He said: "There is a hierarchy of confidence because people spend most of the week on core subjects and less time on technical subjects such as music."
Lynne Betts, acting headteacher at 26-pupil Besthorpe primary near Newark, Nottinghamshire, said: "Personally, I think the national strategies have been great. I love teaching literacy and numeracy."
Teachers were more sure of their ability to teach history than other non-core subjects. Maths and history were the only subjects about which teachers felt completely confident.
Colin Richards, chairman of the National Primary Teacher Education Conference, said: "My feeling is now with national numeracy and literacy strategies, students in initial teacher training could spend a little less time on maths and English and devote more time to the practical subjects."