To provide an exhaust gas purification device for a diesel engine in which a NOx reduction and purification catalyst can be prevented from being broken by penetration of a reductant into a supporting member of the catalyst, while improving performance of the catalyst, a retainer (11) is provided to stand on an inner surface (10) of a connection pipe (8B) at a position between an injection nozzle (7) for aqueous urea and an upstream end surface (5a) of an SCR catalyst (5) and to extend in a circumferential direction, and the retainer (11) is spaced from the upstream end surface (5a) of the SCR catalyst (5).
