A sample producing method of producing an observation sample by placing an observation target object on an optically transparent plate, the method comprising: an arranging step of arranging the plate on a base plate, the base plate including a liquid discharge mechanism and a first lyophobic portion (32D, 32S1, 32S2) at a peripheral edge portion of a portion where the plate is arranged, a forming step of forming a liquid pool by supplying a liquid to a predetermined region on the plate, a placement step of placing the observation target object on a surface of the liquid pool retained on the plate; and a fixing step of - tilting the plate to guide the liquid of the liquid pool to the liquid discharge mechanism at one end portion side of the plate, to regulate a movement of the liquid to the one end portion side by the first lyophobic portion (32D, 32S1, 32S2), wherein a liquid height level is lowered while discharging the liquid from the one end portion side, and to make an amount of the liquid of the liquid pool on the plate larger on the one end portion side than on the other end portion side such that a liquid depth of the liquid pool on the plate becomes shallower on the other end portion side than on the one end portion side, and - attaching and fixing the observation target object to a surface of the plate sequentially from the other end portion toward the one end portion, wherein in the arranging step, the plate is arranged to be adjacent to the first lyophobic portion (32D, 32S1, 32S2). an arranging step of arranging the plate on a base plate, the base plate including a liquid discharge mechanism and a first lyophobic portion (32D, 32S1, 32S2) at a peripheral edge portion of a portion where the plate is arranged, a forming step of forming a liquid pool by supplying a liquid to a predetermined region on the plate, a placement step of placing the observation target object on a surface of the liquid pool retained on the plate; and a fixing step of - tilting the plate to guide the liquid of the liquid pool to the liquid discharge mechanism at one end portion side of the plate, to regulate a movement of the liquid to the one end portion side by the first lyophobic portion (32D, 32S1, 32S2), wherein a liquid height level is lowered while discharging the liquid from the one end portion side, and to make an amount of the liquid of the liquid pool on the plate larger on the one end portion side than on the other end portion side such that a liquid depth of the liquid pool on the plate becomes shallower on the other end portion side than on the one end portion side, and - attaching and fixing the observation target object to a surface of the plate sequentially from the other end portion toward the one end portion, - tilting the plate to guide the liquid of the liquid pool to the liquid discharge mechanism at one end portion side of the plate, to regulate a movement of the liquid to the one end portion side by the first lyophobic portion (32D, 32S1, 32S2), wherein a liquid height level is lowered while discharging the liquid from the one end portion side, and to make an amount of the liquid of the liquid pool on the plate larger on the one end portion side than on the other end portion side such that a liquid depth of the liquid pool on the plate becomes shallower on the other end portion side than on the one end portion side, and - attaching and fixing the observation target object to a surface of the plate sequentially from the other end portion toward the one end portion, wherein in the arranging step, the plate is arranged to be adjacent to the first lyophobic portion (32D, 32S1, 32S2).