A compound represented by the formula (I): ** Formula ** [wherein R1 and R2, which may be the same or different, are each a hydrogen atom, the formula - (CR4R4 ') - O-CO-R5 or - (CR6R6 ') - O-CO-O-R7, or the following formula (IIa) or (IIb): ** Formula ** R3 is a hydrogen atom, the formula - (AA) nH, -CO- O- (CR9R9 ') - O-CO-R10 or -CO-O- (CR9R9') - O-CO-O-R11, or the following formula (III): ** Formula ** where R4 and R4 ' , which may be the same or different, are each a hydrogen atom or a C1-C6 alkyl group； R5 is a C1-C10 alkyl group, a C3-C8 cycloalkyl group, (the C3-C8 cycloalkyl group being optionally substituted with one to three C1-C6 alkyl groups), an adamantyl group (the adamantyl group being optionally substituted with one to three C1-C6 alkyl groups, or a phenyl group (the phenyl group being optionally substituted with one to three groups selected from a halogen atom and a C1-C6 alkyl group)； R6 and R6 ', which may be the same or different, are each a hydrogen atom or a C1-C6 alkyl group； R7 is a C1-C10 alkyl group, a C3-C8 cycloalkyl group, (the C3-C8 cycloalkyl group being optionally substituted with one to three C1-C6 alkyl groups), an adamantyl group (the adamantyl group being optionally substituted with one to three C1-C6 alkyl groups, or an aryl group (the aryl group being optionally substituted with one to three groups selected from a halogen atom and a C1-C6 alkyl group)； R8 is a C1-C6 alkyl group or a phenyl group； R9 and R9 ', which may be the same or different, are each a hydrogen atom or a C1-C6 alkyl group； R10 is a C1-C10 alkyl group, a C3-C8 cycloalkyl group, (the C3-C8 cycloalkyl group being optionally substituted with one to three C1-C6 alkyl groups), an adamantyl group (the adamantyl group being optionally substituted with one to three C1-C6 alkyl groups, or a phenyl group (the phenyl group being optionally substituted with one to three groups selected from a halogen atom and a C1-C6 alkyl group)； R11 is a C1-C10 alkyl group, a C3-C8 cyc
