It is a geometric pattern of repeated alternating dark and light squares. It was named after Sanogawa Ichimatsu, the kabuki actor during the Edo period, who was often dressed in the checkerboard patterned costume on the stage.
This fabric pattern can be often seen on kimono or obi.
Originally, the pattern of ichimatsu is derived from the pattern of arare, which used for clothing worn by the imperial family and court nobles during the Heian period.
The pattern was used for Noh costume or architectural decoration.