Japan's Crown Princess Masako, who has been undergoing treatment for a stress-induced illness for a decade, departed for the Netherlands on Sunday in her first trip abroad in nearly seven years.

Accompanying her husband, Crown Prince Naruhito, the 49-year-old former diplomat left Tokyo Sunday on an official visit to the Dutch capital of Amsterdam to attend the coronation of Willem-Alexander on April 30.

It is her first overseas trip since Naruhito's family spent about two weeks at a retreat in the Netherlands in August 2006 at the invitation of Queen Beatrix.

It is also her first official visit abroad in nearly 11 years since the couple went to New Zealand and Australia in late 2002.

During the couple's six-day trip, Masako is scheduled to attend the Dutch king's coronation but may skip other events "depending upon her condition", the Imperial Household Agency has said.

US-educated Masako has reportedly struggled with the cloistered nature of royal life in one of the world's oldest and most tradition-bound monarchies.

She was diagnosed with an adjustment disorder, according to an official statement in 2004.

Masako married Naruhito, now 53, in 1993 and gave birth to their first and only child, a girl, in late 2001 under intense pressure to bear a son in keeping with Japan's male-only royal succession law.

The pressure seemingly eased when a boy was born to the family of the crown prince's younger brother in 2006, the first prince born to Japan's royal family in 40 years.