While the easing yen is a welcome development for exporting companies, it is slowly starting to cast a shadow on family budgets, pushing up the price of gasoline and other daily necessities.

The average retail price of regular gasoline has gone up for eight consecutive weeks, reaching ¥151.2 per liter Monday, ¥5.7 more than it was on Nov. 26, according to the Natural Resources and Energy Agency.

The weak yen has also pushed up the average retail price of kerosene for nine consecutive weeks, reaching ¥1,792 per 18 liters as of the beginning of this week, an increase of ¥164 since the week of Nov. 19.

The cheap yen has raised the price of some imported foods, and some retailers say if the trend continues it could drive up other daily necessities as well.

Costco Wholesale Japan Ltd. said prices of some products have already been raised due to the weak yen. An employee said there haven’t been any complaints from customers so far.

Seijo Ishii Co., a Yokohama-based supermarket chain that offers many imported food items, said it has not revised its prices so far because a large part of its inventory was imported before the yen started to weaken.

A Seijo Ishii spokeswoman explained that retail prices are influenced by much more than just currency exchange rates. Other factors include changes in the cost of raw materials as well as oil prices, which impact shipping fees.

“At this stage, I really can’t tell how (the yen rate) will affect” Seijo Ishii’s pricing policy, she said, adding that the chain will try to cut costs in other areas to avoid raising product prices.

Nippon Flour Mills Co. said if the weak yen continues for a long time, imported flour prices may rise, a spokesman said.

“We are watching closely (the effects of the easing yen). I can’t say anything other than that. It’s not like we can do anything to stop” prices from rising, the spokesman said.