PROBLEM TO BE SOLVED: To provide an auxiliary device for mulching culture, capable of preventing ridge temperature decrease caused by wind getting-in through a hole bored in a mulching sheet, easy in supplying water, also capable of collecting rain water and the like to utilize the same as water supply, further capable of making easy the water infiltration to the ridge by extending the mulching sheet hole, and furthermore serving to hold the mulching sheet. SOLUTION: The auxiliary device includes a body 2 of an upper surface opened-container shape and blockading with a bottom surface 2a a hole 1a bored in a mulching sheet 1, and a stick-shape element 4 for holding the body 2 on a ridge 3 through the mulching sheet 1. A hole 2b for passing a seedling 5 is bored in the almost center of the bottom surface 2a of the body 2. The body 2 is formed to be bisected at the hole 2b position. Further, a push-in part 6 to be pushed in the ridge 3 through the mulching sheet 1 is formed at the lower side of the bottom surface 2a, to be a height shape around the hole 2b to center the hole 2b. COPYRIGHT: (C)2013,JPO&INPIT