The fire services department said that a landslide occurred on Sunday at the mine, located near the village of Kayin Chaung, in the northern state of Kachin.
Authorities said that 15 employees of the Yaza Htarni Jade Mining Company and three policemen who were providing security were killed in the landslide, while another two police officers were injured.
The death toll is expected to continue rising as the search-and-rescue operation is still ongoing, reported Efe news.
Accidents inside jade mines are a common occurrence in Myanmar.
In April, at least 54 people died in another landslide at a mine in Hpakant, a remote area located about 800 kilometers (497 miles) north of the capital, Naypyidaw.
The non-profit Global Witness denounced in 2015 the precarious situation in which jade miners work in sites that are often exploited by guerrilla organisations, warlords, drug traffickers and corrupt members of the army, among other groups.
Thousands of Myanmar youth come to Hpakant, the so-called "Land of Jade," with the hope of escaping poverty and making money through jade mining.
But many of these migrant workers instead become addicted to cheap heroin and other drugs.
Although the Hpakant area is a harsh and poor region, it generates vast amounts of wealth for some, as buried within its soil are significant deposits of the rare mineral jadeite, the world's highest-quality type of jade.
( With inputs from IANS )