The present invention provides a vinylether compound of the following general formula (1), wherein R.sup.1 represents a monovalent hydrocarbon group having 1 to 15 carbon atoms, and the wavy line represents the E-form, the Z-form, or a mixture thereof. The present invention further provides a process for preparing 2,3,4,4-tetramethyl-1-cyclopentenecarbaldehyde of the following formula of the following formula (2), the process comprising subjecting the vinylether compound (1) to a hydrolysis reaction to form 2,3,4,4-tetramethyl-1-cyclopentenecarbaldehyde (2). ##STR00001##