By 2016 there were 1,402 language teachers, down from 1,635 in 2010, according to data from the Scottish government.
The staffing decline has prompted more concerns about the dwindling number of pupils taking exams in German, French and Italian in recent years despite policies to reverse the trend.
Tavish Scott, education spokesman for the Scottish Liberal Democrats, who asked for the figures to be published, said: “It’s extremely disappointing to see such a dramatic fall in the number of secondary school language teachers since 2010.
“Language teaching in schools has been highlighted as a government priority yet the government’s own figures show there are fewer teachers than before, setting language students up for failure.
“If the Scottish government is serious about getting pupils learning languages, then they need to ensure every school has the resources to provide a quality language education.”
A spokeswoman for the Scottish Association of Language Teaching (SALT) said the fall was “hugely concerning” and stemmed from curriculum changes. Pupils are meant to have access to languages throughout the first three years of secondary education but sometimes options are being narrowed earlier.
The spokeswoman said: “While learners have the entitlement to a language to the end of the broad general education in S3, we are hearing worrying reports that students are not able to access languages after the second year.”
SALT also said schools were limiting the number of subjects that pupils could study in fourth year.
The spokeswoman added: “The perception that languages are just too hard desperately needs to be demystified.”
There is no excuse for any child not to have a good language learning experience, she said.
The Scottish government highlighted its 1+2 policy, where pupils are to be taught at least two modern languages as well as their native tongue by the time they leave primary school. Local authorities have said the policy lacks adequate funding, and some language experts have argued against too many languages being pursued.
A government spokeswoman said: “We have increased (overall) student teacher intake targets for the fifth year in a row, and we are setting targets to train teachers in the subjects where they are needed most.”