An acid gas absorbent includes at least one kind of secondary amine compound represented by formula (1): where R1 is a cyclopentyl group or a cyclohexyl group which may be substituted by a substituted or non-substituted alkyl group having 1 to 3 carbon atoms, R2 and R3 each indicate an alkylene group having 2 to 4 carbon atoms, and R2 and R3 may each be the same or different, and be a straight chain or have a side chain.