This paper presents sensitivity analysis for generalized rapid relaxation inversion (GRRI) algorithm, which was originally developed by modifying the RRI algorithm to recover a two-dimensional (2-D) conductivity structure from MT data, to interpret controlled-source audio-frequency magnetotelluric (CSAMT) data. The GRRI algorithm can be extended to invert CSAMT data if it is combined with 2.5-D forward modeling including a source effect. GRRI approximate sensitivities are validated by comparing with exact 1-D and 2.5-D sensitivities. The comparison shows that the GRRI sensitivity is a good approximation to the exact sensitivity and has about half magnitude of the RRI sensitivity. Although the magnitude of the GRRI sensitivity is still slightly larger than that of the 2.5-D sensitivity, both sensitivities are broadly similar in shape when source-receiver offsets are greater than one skin depth in the earth. This suggests that the GRRI approach can be successfully used to invert CSAMT data through some scalling of sensitivities.