Automatic tissue staining device and automatic tissue staining method

An automatic tissue staining device comprising:

• a supply head configured to supply a treatment fluid;
• a horizontal direction movement unit configured to move the supply head in a horizontal direction;
• a holding unit configured to hold a plurality of glass slides on which samples are set, the holding unit including a first region and a second region different from the first region;
• and
• a control unit configured to judge an occupancy status of the horizontal direction movement unit in a condition that one or more of the glass slides are situated in the first region, prior to supply of the treatment fluid from the supply head to one or more samples on the one or more glass slides situated in the first region;
• suspend a start of a soonest treatment for the one or more samples on the one or more glass slides situated in the first region when the horizontal direction movement unit is occupied;
• and permit the start of the soonest treatment for the one or more samples on the one or more glass slides situated in the first region when the horizontal direction movement unit is not occupied.