To provide a microcapsule which shows a high color development density best-suited for a heat-sensitive recording material and a multi-color heat-sensitive recording material and an outstanding fresh shelf stability and the heat-sensitive recording material using the microcapsule.

This microcapsule is characterized in that at least, a capsule wall is formed by adding a diazonium salt compound represented by formula (1) and an aromatic carboxylic acid compound represented by formula (2) and using a difunctional isocyanate compound having two isocyanate groups in one molecule represented by formula (3) and a polyfunctional isocyanate compound having not less than three isocyanate groups in one molecule, as core substances. In addition, the heat-sensitive recording material using the microcapsule is provided. In the formula, R11 to R15 are a substituted or a non-substituted alkyl group, aralkyl group or aryl group. R12 and R13 or R14 and R15 may form a ring with a nitrogen atom. X is an acid anion.