According to one embodiment, a tablet printing apparatus includes: a conveyor belt configured to convey a tablet； a print head configured to perform printing on the tablet conveyed by the conveyor belt； and a belt-position detector configured to detect the position of the conveyor belt in a direction crossing the conveying direction of the tablet in a horizontal plane. The conveyor belt includes a plurality of holes arranged in a row along the conveying direction of the tablet to hold the tablet. The belt-position detector includes an imaging device configured to capture an image of two or more of the holes； and an image processing device configured to detect the position of the conveyor belt in the crossing direction based on the image captured by the imaging device.
