Sales at supermarkets fell 2.5 percent in January from the year before on a same-store basis while department store sales dipped 0.4 percent, industry groups said Friday.
The Japan Chain Stores Association said sales at 8,751 outlets run by its 93 member supermarket chains totaled 1.24 trillion yen in the reporting month.
The Japan Department Stores Association reported that sales at 284 stores run by 96 member companies came to 691.3 billion yen in the month.
Both associations attributed the sales fall to the deterioration in weather in the latter half of January, when heavy snow deterred many people from going out to spend.
January sales at supermarkets marked the first fall in two months, while those at department stores signified the first fall in five months, according to the two industry bodies.
A senior official of the department stores association said, "We cannot detect strength in the nation's personal spending," as merchandise sectors and areas where its member outlets are seeing sales improvements are limited.
Personal consumption accounts for more than half of Japan's gross domestic product.