Tatami Mat Day (Tatami no Hi)

What Is Tatami Mat Day?

Every year on April 29, Japan observes "Tatami no Hi" (Tatami Mat Day). It was established in 1997 by the National Tatami Industry Promotion Association (Zenkoku Tatami Sangyō Shinkōkai). April 29 — then called "Greenery Day" — was chosen because it is the season when igusa rush, the raw material of tatami, grows and turns the paddies green. September 24 is also designated as an autumn Tatami Day, making it a day observed twice a year.

The History of Tatami and Japan's Housing Culture

Tatami has a long history — the "goshō no tatami" preserved in the Shōsōin repository in Nara, associated with Emperor Shōmu, is considered the oldest surviving tatami. Originally, it wasn't used to cover entire floors, but as a seating mat reserved for people of high status.

• Heian period: Used in the living spaces of the aristocracy
• Muromachi period: Spread to cover entire rooms alongside the rise of shoin-zukuri architecture
• Edo period: From the mid-Edo period, spread to ordinary townspeople's homes (in rural areas, it is said to have spread only after the Meiji era)

The Structure and Materials of Tatami

Tatami mats are made by combining several different materials.

• Tatami-doko (core): The inner core, traditionally made from rice straw or other building materials
• Tatami-omote (surface): The woven surface layer, mainly made from rush grass (igusa)
• Tatami-beri (edging): Reinforces the sides of the mat and also serves a decorative purpose

Differences in materials and manufacturing methods affect the feel underfoot and the mat's durability.

Facts About the Functionality of Tatami

Tatami isn't just about appearance — it has functions that genuinely affect the living environment.

• Humidity regulation, absorbing and releasing moisture
• Sound absorption, softening everyday noise
• Cushioning that reduces impact in case of a fall

These qualities are said to be among the reasons tatami has remained a fixture in Japanese homes for so long.

Fun Facts About Tatami Mat Day

• The spring Tatami Day (April 29) reflects the green season of igusa and the former "Greenery Day"
• The autumn Tatami Day (September 24) is also "Cleaning Day," encouraging people to lift and clean their tatami before the seasonal change of clothes
• It's a day to focus on tatami, a flooring material unique to Japan
• It's deeply connected to housing and architectural culture
• Tatami is still used today in Japanese-style rooms and tea ceremony rooms

Ideas for Spending Tatami Mat Day

• Check the condition and type of any tatami in your home or nearby facilities
• Look into tatami sizing standards (such as Kyoma and Edoma) and how they vary by region
• Research where rush grass (igusa) is grown and how production has changed over time
• Find out how tatami is maintained and how the surface is replaced
• Trace how tatami culture has changed alongside the rise of Western-style rooms

A Day to Reconsider the Culture of "Laying Things Down"

April 29's Tatami Mat Day is a day to take a fresh look at tatami, which has supported Japan's residential culture from the ground up. Tatami has never been just a flooring material — it has been deeply intertwined with lifestyles and architectural styles. This day is a meaningful opportunity to think about the relationship between our everyday living spaces and culture.