source of anxiety; reason for concern
Refers to a specific thing, situation, or thought that causes worry or unease. Often used when identifying what is making someone anxious.
His health condition is a source of anxiety.
The future has become a reason for concern.
Compound of 不安 (anxiety) + の (possessive particle) + 種 (seed, source). Literally 'seed of anxiety', a common metaphorical pattern in Japanese for the origin or cause of something.