Depression and other mental illnesses are on the rise among nursing care workers for the elderly in the country, an apparent reflection of difficult working conditions amid the industry's chronic staff shortages.

The number of workers in the social security, social welfare and nursing care category who applied for workers' compensation for mental illnesses was 140 in fiscal 2014, more than double the 66 recorded in fiscal 2009, according to data from the Health, Labor and Welfare Ministry.

The 140 reported cases, more than double the earlier figure, makes caregivers for the elderly the most affected among all occupations categorized by the government.

In fiscal 2014, 32 workers in the category were awarded workers' compensation for mental illnesses, more than tripling the 10 in fiscal 2009, the data show.

The ministry said many of the affected workers in the category are nursing care staff. Low wages and poor working conditions are widely blamed for the shortage of workers in the sector.