A yeast including a cell wall having a low mannan content, wherein the yeast has an immunopotentiating capability, and is able to grow in a YPD liquid medium with an osmotic pressure of 300 mOsm, and wherein, when a part of a pre-culture of the yeast grown in a YPDS liquid medium is added to the YPD liquid medium so that OD660 is adjusted to 0.1, followed by incubating at 30° C. for 24 hours, the yeast grows to increase the OD660 of the YPD liquid medium to 1.0 or more.
