Method of processing light sensitive planographic printing plate precursor and pre-washing solution used in the method

A method of processing a light sensitive planographic printing plate precursor comprising a support, and provided thereon, a light sensitive layer and an overcoat layer in that order, the method comprising the steps of:

• imagewise exposing the light sensitive planographic printing plate precursor;
• pre-washing the exposed light sensitive planographic printing plate precursor with a pre-washing solution in the presence of a compound represented by the following formula (1) or (2), or an N-alkyliminodiacetic acid or its salt, the alkyl having a carbon atom number of 1 to 3;
• and
• developing the pre-washed light sensitive planographic printing plate precursor with a developer,
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• wherein A1, A2, A3, and A4 independently represents —CH2OH, —PO3(M1)2, or —COOM, in which M and M1 independently represent a hydrogen atom, an ammonium group, an alkali metal atom or an organic ammonium group, and may be the same or different;
• and X represents an alkylene group having a carbon atom number of 2 to 4 or —(B1O)n—(B2)-, in which B1 and B2 independently represent an alkylene group having a carbon atom number of 1 to 5, and may be the same or different, and n is an integer of 1 to 8,
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• wherein X, Y and Z independently represents —CH2—, —(CH2)2—, or —CHOH—, and n is 0 or 1.