Tokyo — It is becoming harder to own a house in Japan. A recent newpaper editorial said bluntly: ''Ordinary people nowadays face certain financial ruin to buy land and build their own house because of the strain of repaying loans.''
And a bank survey found 100,000 home owners currently unable to cope with this strain, with bad debts averaging some $40,000.
Over the past 30 years most of Japan's population (currently about 118 million) has migrated to major urban centers, especially Tokyo, creating an insatiable demand for land - always short in this largely mountainous country - and helping to push real estate prices up.
Tokyo workers have had to look farther and farther beyond the metropolitan boundaries for a small plot of land that suits their purse. Some new housing developments being promoted for Tokyoites are in areas that will involve at least four hours of commuting each day.
Government statistics for 1981 show 61.1 percent of households nationwide owned their own homes, but in Tokyo and surrounding suburban areas, the figure was slightly below 40 percent.
The National Land Agency says the average commuting time for Japanese is already more than twice that of residents of ''standard metropolitan areas'' in the United States.
Even living far out of town no longer guarantees a lighter financial burden. In areas an hour or more traveling time from metropolitan Tokyo, a 200 square meter lot (fairly large by Japanese standards) sells for $150,000 to $180,000. A price of $2,600 or so per square meter is regarded as ''a pretty good bargain.''
With housing construction and material costs also rising, and with taxes and other fixed costs added, no family can expect to move into a newly built home for less than $230,000 these days. That gets them a modest wooden three- or four-bedroom home with a minuscule garden.
The financial costs to many families were put in context by the government's latest report on national life: The average worker's monthly salary is about $ 900. This is cited as one reason half of the nation's 30 million housewives now work part or full time to help share the load.
A housewife recently wrote to a national newspaper to describe how she and her husband bought a privately built apartment four years ago. ''Ever since, we have been paying back the debt, sacrificing everything. . . . My husband and I are indignant at the government's lack of land and housing policy and curse our fate, as it seems the sole objective of our life is to buy an adequate habitat.''
The National Land Agency says housing loans constitute 92 percent of total household debt, compared to 80 percent a decade ago.
Millions of lower-paid workers have had to buy or rent from the government housing corporation, which tends toward functional but not particularly attractive large apartment complexes. The corporation's policy has been to allot 70 percent of units for sale and the rest for rent.
Even apartments are becoming prohibitively expensive due to the high cost of land, and the corporation increasingly is having trouble finding buyers for units in unattractive, distant locations.
The housewife quoted earlier reported that her family had won a lottery to buy a public apartment. But the debt is twice as large as before.
Government officials concede she is fairly typical, but they add there are no easy solutions.
More and more, it seems, families will have to give up the dream of owning their own home. Industry analysts say private builders and the housing corporation to concentrate in the future on rental units.
The biggest problem remains the high cost of land. Various ideas are being considered to alleviate this. One draws on the US example of redeveloping and revitalizing rundown central city areas with high-rise apartment complexes. Another is to encourage business to move out of the cities to be nearer their work forces.