A process for producing t-butoxycarbonylamine compounds, comprising an use of phosgene, diphosgene or triphosgene, t-butanol, an organic base and a primary or secondary amine compound or primary or secondary ammonium salt, which includes any one of following processes (a) to (f): (a) a process comprising an addition of a solution containing a primary or secondary amine compound and an organic base to a solution containing phosgene, diphosgene, or triphosgene and t-butanol, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (b) a process comprising an addition of a solution containing a primary or secondary amine compound, an organic base and t-butanol to a solution containing phosgene, diphosgene, or triphosgene, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (c) a process comprising a substantially simultaneous addition of a solution containing a primary or secondary amine compound, a solution containing an organic base and a solution containing phosgene, diphosgene, or triphosgene to a solution containing t-butanol, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (d) a process comprising an addition of a solution containing a primary or secondary amine compound and a solution containing an organic base to a solution containing t-butanol while blowing in phosgene gas, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (e) a process comprising an addition of a solution containing t-butanol, a primary or secondary amine compound and an organic base to a reaction solution while blowing in phosgene gas, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; and, (f) a process comprising an addition of an organic base to a solution containing phosgene, diphosgene, or triphosgene, t-butanol and a primary or secondary ammonium salt, at the addition rate that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules, wherein the primary or secondary amine is a compound represented by a formula shown below, and the primary or secondary ammonium salt is a salt comprised of a primary or secondary amine represented by the formula and an acid: wherein R represents a C1-6 alkyl group, C1-6 haloalkyl group, halogen atom or group represented by formula (a) shown below: wherein * represents the bonding site to the pyridine ring of formula, and n represents the substitution number of R that is an integer of 0 to 4, and R may be the same or different when n is 2 or more. (a) a process comprising an addition of a solution containing a primary or secondary amine compound and an organic base to a solution containing phosgene, diphosgene, or triphosgene and t-butanol, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (b) a process comprising an addition of a solution containing a primary or secondary amine compound, an organic base and t-butanol to a solution containing phosgene, diphosgene, or triphosgene, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (c) a process comprising a substantially simultaneous addition of a solution containing a primary or secondary amine compound, a solution containing an organic base and a solution containing phosgene, diphosgene, or triphosgene to a solution containing t-butanol, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (d) a process comprising an addition of a solution containing a primary or secondary amine compound and a solution containing an organic base to a solution containing t-butanol while blowing in phosgene gas, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; (e) a process comprising an addition of a solution containing t-butanol, a primary or secondary amine compound and an organic base to a reaction solution while blowing in phosgene gas, wherein the addition rate is such that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules; and, (f) a process comprising an addition of an organic base to a solution containing phosgene, diphosgene, or triphosgene, t-butanol and a primary or secondary ammonium salt, at the addition rate that the amount of free primary or secondary amine compound is 0.31 moles or less per 1 mole of phosgene molecules, wherein the primary or secondary amine is a compound represented by a formula shown below, and the primary or secondary ammonium salt is a salt comprised of a primary or secondary amine represented by the formula and an acid: wherein R represents a C1-6 alkyl group, C1-6 haloalkyl group, halogen atom or group represented by formula (a) shown below: wherein * represents the bonding site to the pyridine ring of formula, and n represents the substitution number of R that is an integer of 0 to 4, and R may be the same or different when n is 2 or more.