1. A roe maturity determination device comprising components configured to irradiate roe with light from below the roe, take an image of the irradiated light passing through the roe from above the roe and determine maturity of the roe on a basis of the image, the device further comprising: a loading tray comprising a light transmissive material, on which the roe is loaded; a conveyor that moves horizontally below the loading tray to convey the loading tray in a conveyance direction; a support comprising a rotatable portion configured to slant the loading tray in a lateral direction orthogonal to the conveyance direction, the rotatable portion capable of changing a position of the loading tray from a loading position to load the roe thereon to an output position to let the roe out to a side of the conveyor, the support between the conveyor and the loading tray and supporting the loading tray above the conveyor, the support further defining a space between the conveyor and the loading tray, the space extending over the conveyance direction of the loading tray and having one open side in the lateral direction; and a light irradiation device disposed at a height between the conveyor and the loading tray and extending in the lateral direction into the space through the open side, the light irradiation device including a light emission portion extending from one side of the loading tray to the other side of loading tray in the lateral direction, such that irradiated light from the light emission portion passes through the space.