An oil level gauge guide structure including an oil level gauge for measuring engine oil of a vehicle. An oil level gauge is held in an oil level gauge guide. A clip is provided having a first end section held to a resinous part fixed to an engine main body, and a second end section held to the oil level gauge guide. The oil level gauge is provided with two linear stoppers contactable with the second end section of the clip, and an O-ring fixed on an end section of the oil level gauge guide. The end section of the oil level gauge guide is inserted into the communication hole in a first direction, while the first end section of the clip is pressed to the resinous part in a second direction. The first and second directions are parallel with each other.