Recently, post processing using helium ion irradiation has attracted attentions to improve the performance of superconducting nanostrip photon detector (SNSPD) [1]. The post processing requires to use of SNSPDs with front-illuminated structure rather than back-illuminated structure. Here, we report the fabrication of SNSPD with frontside illuminated and self-aligned structure. NbTiN and MoN were used as superconducting materials. MoN is known to be a good candidate for high-performance SNSPDs [2]. Ultrathin films of NbTiN and MoN with a thickness of 10 nm were grown using the magnetron sputtering, and the films were processed into meandering fine wires with a linewidth of 100-200 nm using conventional electron beam lithography and reactive ion etching. Then they were cut into disk shapes with a diameter of 2.5 mm using deep etching with SF6 and C4F8. After the fabrication, the device characteristics were optimized using He ion irradiation, and the focusing position was self-aligned by inserting it into an optical fiber sleeve with an inner diameter of 2.5 mm. SNSPDs with saturated detection efficiency were obtained.