An ink according to an embodiment includes a functional layer forming material, wherein the ejection amount of a droplet ejected from a nozzle of an inkjet head is 9.5 ng or more and 11 ng or less, and the length of the droplet when the droplet is ejected from the nozzle at an ejection velocity of 6 m/sec or more and 9 m/sec or less is 250 μm or less.